The play count has reset to 0 for many songs

I know I didn't do it. I keep close watch on the play count because I have a playlist called "Least played" (fewer than 10 times) and "Less played (fewer than 26 times). My library has fewer than a dozen recent additions (i.e., since the last time I opened Music), but the Songs view now lists nearly 1,000 tracks with 0 plays. I can recall a similar incident maybe a year ago; another reason I keep tabs on the play count.

Q1: Why does this happen?

Q2: Should I make a list of recent additions and restore backups until I see counts that look right?

Q3: If Q2 is yes, should I upgrade to iOS 18 before or after, or does it matter?

Thanks.

Mac OS Sonoma 14.6.1

iOS 17.7