Merge request info is lost when merging squashed commits with fast-forward policy
After merging MR with both "Squash commits" option and "Fast-forward merge" options enabled the MR information (link) is lost when looking at the commit history.
I don't know if this qualifies as a bug or a feature, I'm guessing you are using the commit hash to identify related MR. But since this hash is changed after squashing, it's harder to link the new hash to the MR.