Zend certified PHP/Magento developer

Magento 2.4 special price reverting when qty updates

I have a special price set on some products in Magento 2.4. The price works fine when you put an original QTY in (on the cat page, product page, minicart or cart page) but as soon as the qty is changed the price reverts to the base price. No matter where the qty is updated this is happening and i don’t know where to start to fix this issue.

We have recently upgraded to 2.4 and ive just noticed it but it may have been happening before the upgrade.

This is when an original quantity is put in and works as expected.
This is when an original quantity is put in and works as expected.

This is when the qty is changed:
enter image description here

This is happening anywhere the qty can be changed.