During the height of the quarantine last year I managed the live-streaming of the traditional form of the Catholic Mass (1962 Missal, substantially the same ruberics and ceremonials from the fifth century until the 1960s) at a local parish and on EVERY Sung High Mass there were multiple copyright flags applied because the liturgical hymns sung by the choir, the "newest" of which averaged 250 years in age and some of which were over a thousand years old, were part of a commercial recording by some professional choral ensemble. Had someone played a CD of that professional recording in the chapel then this would have been a copyright violation, but it's OBVIOUS to any human who listens to the sound on those videos that this was a live performance -- by volunteer, part-time singers who make lots of mistakes -- of works that have been in the public domain for centuries.
This system is clearly a CYA for Google: they would rather flag videos and PERMANENTLY demonetize content creators based on repeated false positives (but still show advertisements on the videos anyway!) than to risk even the remotest chance that a content creator might sue YouTube for enabling copyright infringement.