I was going through my contacts and discovered many of them had a 4-digit number appended to the end of the first line of the physical address (123 Mystreet Ln 4032 instead of 123 Mystreet Ln.). I couldn't find a previous bug report on this. I don't know if this happened on the Google side or the Outlook side (vs 2019). I had to go through and manually correct about 30 addresses. Also, all of the addresses affected ended with a non-punctuated suffix. Since I normally punctuate my suffixes, I'm wondering if that caused the sync to barf at some point. My usual treatment is 123 Mystree Ln. with a period on the end. Same for Cir., Rd., Blvd., etc. The 4-digit numbers were seemingly random.
I have sync set to merge prompt. Just to clean things up though, I ran GCSM in Merge Outlook Wins mode. It's set back to merge prompt. I'll see if this happens again. If it's a known problem that was fixed, feel free to mark this CLOSED.