Quality gate fails unexpectedly for old code

The newer project provokes a warning about a shallow clone from sonar whereas the other didn’t.
Are you able to discern from your side whether there are cases where an analysis could fail to produce such a warning?

Unfortunately I can’t easily restart the merge that demonstrated it as it has already been completed.
It might be possible if I create a clone of the project and undo the change and try to reapply it. It requires a bit of jumping through hoops and time which I may or may not be able to justify.

The default for azure was a deep clone when the project was first onboarded but it is not impossible that it became shallow for the pull request. I would expect the sonar analysis to have detected that however.