Every cat we’ve ever had very clearly understood mirrors. If that’s really the conventional view of scientists in the field, that’s basically willful ignorance.
Understanding how to track others in mirrors is one thing -- understanding with clarity that the cat in the mirror is them, is actually another.
The mirror dot test (which I imagine needs to be done really carefully with cats since they instinctively clean their own faces and necks, and have sensitive whiskers) shows whether the animal fully understands that the reflection is specifically of them, and can use that reflection to solve a puzzle.
I have said elsewhere that it's kind of just about possible for the ears-in-the-mirror cat to not understand the mirror cat is herself, but it is an increasingly implausible alternative.
The mirror dot test may have its limitations on a species basis, but it is not easy to come up with a universal test.
There really is a conventional scientific view that cats are not capable of passing typical mirror-related self-awareness tests.
But it strikes me that the problem might be that the tests just aren't designed to test cats.