In gitlab is there a setting that affects if an approval for an MR is invalidated after a new commit is pushed? I have seen that in some setups a new commit invalidates the approval but in others not so wondering what is the difference
Merge request approval settings including "Remove all approvals when commits are added to the source branch" are configurable per project. These settings also require a Premium subscription.
So, you may experience differences based on how the project is configured or the subscription level of the customer/instance.