To What Degree does iTunes Match change existing iTunes Art & Tag Data?

Will current iTunes Match / Apple Music / iCloud Music Library change existing album art and/or meta data for tracks in my iTunes for Mac Music Library ...and if so, is there a way to ensure iTunes Match will NOT change anything in my existing tracks?

I have a heavily curated library of over 26K tracks in iTunes (~20% purchased from iTunes), with album/track art and ID3 data that is consistent and matches the physical media I own. I have twice tried to use iTunes Match since it first became available years ago, but each time found within a few days/weeks that iTunes Match changed some of the physical track art and/or meta tagging within my iTunes library without my giving it explicit permission -- undoing man weeks of careful changes I have made over many years. Both times I ended-up turning-off iTunes Match in iTunes and my other Apple devices, physically restoring, then manually re-syncing changes I had made to my local iTunes library since enabling iTunes Match. It was frustrating to say the least -- especially sort of doing it to myself a second time-around.

Through this process, I found that maintaining "iTunes Preferences / Store / Auto download album artwork = OFF" eliminated some spurious problems I occasionally encountered with unexpected things happening to Album Art, and keep that option set OFF to this day, but I don't know if that may now also effect iTunes Match. In searching the WWW, support documents and this forum, I see some people may be still encountering similar problems to what I have before, but it's hard to tell timeline-wise.

Can anyone provide me any confidence if I try iTunes Match (or Apple Music) for a 3rd time, that iCloud Music Library will NOT change my existing iTunes Album Art and tag data? Thx in advance.