“Use by default” unchecks in category settings – after adding products to category through 3rd party system

We have been using a 3rd party ERP system for years and it’s always worked without many issues.

However since magento 2.4.5 whenever we add a product to a category, all the settings in said category get the “use by default” box unticked:

The owners of the system say it’s unrelated to their system because they don’t use any calls to make changes to the category. They use:
catalogCategoryLinkRepositoryV1SaveRequest,
catalogCategoryManagementV1GetTreeRequest

Has anyone experienced similar issues? I’ve seen many threads where the box got unticked for product settings but none for any category related ones.

Thanks in advance