how to save extension attribute in salesrule Api magento 2.4

I need to save custom field data in apply_on_weekday column which is located at salesrule Db table. I tried to much but it doesn’t save it in db. i share my code.

vendorModuleetcextension_attributes.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Api/etc/extension_attributes.xsd">
    <extension_attributes for="MagentoSalesRuleApiDataRuleInterface">
        <attribute code="apply_on_weekday" type="string[]" />
    </extension_attributes>
</config>

VendorModuleviewadminhtmlui_componentsales_rule_form.xml

<?xml version="1.0" encoding="UTF-8"?>
<form xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Ui:etc/ui_configuration.xsd">
    <fieldset name="rule_information" sortOrder="10">
        <field name="apply_on_weekday" formElement="multiselect">
            <argument name="data" xsi:type="array">
                <item name="config" xsi:type="array">
                    <!-- <item name="dataType" xsi:type="string">int</item> -->
                    <item name="source" xsi:type="string">sales_rule</item>
                    <item name="default" xsi:type="string">Mon</item>
                </item>
            </argument>
            <settings>
                <label translate="true">Apply for specific weekdays</label>
                <dataScope>apply_on_weekday</dataScope>
            </settings>
            <formElements>
                <multiselect>
                    <settings>
                        <options class="VendorModuleModelConfigSourceWeekdays"/>
                    </settings>
                </multiselect>
            </formElements>
        </field>
    </fieldset>
</form>

VendorModuleModelConfigSourceWeekdays.php file

<?php

namespace VendorModuleModelConfigSource;

use MagentoFrameworkDataOptionSourceInterface;

class Weekdays implements OptionSourceInterface
{
    /**
     * Value which equal "Monday" for Weekdays dropdown.
     */
    const MONDAY = "Mon";

    /**
     * Value which equal "Tuesday" for Weekdays dropdown.
     */
    const TUESDAY = "Tue";

    /**
     * Value which equal "Wednesday" for Weekdays dropdown.
     */
    const WEDNESDAY = "Wed";

    /**
     * Value which equal "Thursday" for Weekdays dropdown.
     */
    const THURSDAY = "Thu";

    /**
     * Value which equal "Friday" for Weekdays dropdown.
     */
    const FRIDAY = "Fri";

    /**
     * Value which equal "Saturday" for Weekdays dropdown.
     */
    const SATURDAY = "Sat";

    /**
     * Value which equal "Sunday" for Weekdays dropdown.
     */
    const SUNDAY = "Sun";

    /**
     * {@inheritdoc}
     */
    public function toOptionArray()
    {
        return [
            ['value' => self::MONDAY, 'label' => __('Mon')],
            ['value' => self::TUESDAY, 'label' => __('Tue')],
            ['value' => self::WEDNESDAY, 'label' => __('Wed')],
            ['value' => self::THURSDAY, 'label' => __('Thu')],
            ['value' => self::FRIDAY, 'label' => __('Fri')],
            ['value' => self::SATURDAY, 'label' => __('Sat')],
            ['value' => self::SUNDAY, 'label' => __('Sun')],
        ];
    }
}

VendorModuleetcdi.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <type name="MagentoSalesRuleApiRuleRepositoryInterface">
        <plugin name="vendor_module_rule_repository_plugin" type="VendorModulePluginModelRuleRuleRepositoryPlugin"/>   
    </type>
</config>

VendorModulePluginModelRuleRuleRuleRepositoryPlugin.php

<?php 

namespace VendorModulePluginModelRule;

use MagentoSalesRuleApiDataRuleExtensionFactory;
use MagentoSalesRuleApiDataRuleExtensionInterface;

class RuleRepositoryPlugin
{
    /**
     * Rule Extension Attributes Factory
     *
     * @var RuleExtensionFactory
     */
    protected $extensionFactory;

    /**
     * RuleExtensionFactory constructor
     *
     * @param RuleExtensionFactory $extensionFactory
     */
    public function __construct(RuleExtensionFactory $extensionFactory)
    {
        $this->extensionFactory = $extensionFactory;
    }

    public function afterSave(
        MagentoSalesRuleApiRuleRepositoryInterface $subject,
        MagentoSalesRuleApiDataRuleInterface $entity
    ) {
        $rule = $entity;
        /** Get Current Extension Attributes from Rule 
         * @var MagentoSalesRuleApiDataRuleExtensionInterface|null
         */
        $extensionAttributes = $rule->getExtensionAttributes();
        $extensionAttributes = $extensionAttributes ? $extensionAttributes : $this->extensionFactory->create();
        $applyOnWeekday = $extensionAttributes->getApplyOnWeekday();

        var_dump($applyOnWeekday);
        if($applyOnWeekday != null) {
            if(is_array($applyOnWeekday)) {
                $applyOnWeekday = implode(',', $applyOnWeekday);
            }

            $rule->setData('apply_on_weekday', $applyOnWeekday);
        }

        return $rule;
    }
}

Now we call API for create salesrule

Endpoint :- rest/default/V1/salesRules

Method :- POST

paylod:-

{
    "rule": {
        "name": "testing the string",
        "store_labels": [],
        "description": "",
        "website_ids": [
            1
        ],
        "customer_group_ids": [
            1
        ],
        "from_date": "2022-10-31",
        "uses_per_customer": 0,
        "is_active": true,
        "condition": {
            "condition_type": "Magento\SalesRule\Model\Rule\Condition\Combine",
            "aggregator_type": "all",
            "operator": null,
            "value": true
        },
        "action_condition": {
            "condition_type": "Magento\SalesRule\Model\Rule\Condition\Product\Combine",
            "aggregator_type": "all",
            "operator": null,
            "value": true
        },
        "stop_rules_processing": true,
        "is_advanced": true,
        "sort_order": 0,
        "simple_action": "by_percent",
        "discount_amount": 0,
        "discount_step": 0,
        "apply_to_shipping": false,
        "times_used": 0,
        "is_rss": true,
        "coupon_type": "NO_COUPON",
        "use_auto_generation": false,
        "uses_per_coupon": 0,
        "simple_free_shipping": "0",
        "extension_attributes": {
            "apply_on_weekday": [
                "Fri",
                "Sat",
                "Sun"
            ]
        }
    }
}