why would my OneDrive suddenly be processing over 40,000 changes?

Happening for me too. Notable; it processes way slower than usual, no changes listed in the little menu when clicking on the little icon, no big chances made to files in days.

This worked for me and is a really simple fix. Thanks.

Same for me. Build version: 25.070.0413.0001
Never-ending processing, even if I don't change anything.
If I change, it simply doesn't get there, because of the hundred-thousands non-existing "changes" it works on...
Reintsall, unlink-relink didn't help. Annoying... :(

I have two laptops syncing to my Personal One Drive (1TB). The second work PC also has a Onedrive sync to a OneDrive Business (100 TB)
The interesting part is that my personal use laptop remains every time I boot it up getting to ~500k files to change. The business laptop shows for the same personal Onedrive even over 1M (million) changes to process. Like double amount. On both laptops Onedrive processes like 1-2 files per sec, terrible slow.
You can calculate that this takes days, weeks even to get in sync, if ever. However my laptops go to sleep or shutdown at the end of the day. Although I left one running for over 2 days. So the cycle of having 500k or 1M changes to process never gets broken. Every time I bootup the PC they get first to this high number of thousands of files. Then it starts slowly counting down, I do see that.

Note: On the Business laptop the Onedrive Business (100 TB of available storage) remains 100% in sync so far with also literally thousands of files on the Onedrive Cloud. Hence so far no issues.

0x8007017c

this is the error code