Just chiming in with my experience with this issue as well. I’ve been experiencing this for about five months with Obsidian Sync. Primary platforms being synced are iOS, Linux, and Windows. On my iPhone, it is not linked to iCloud.
This morning, I saw that I had some duplicate sections in a note I edited around 6pm yesterday. The strange thing was that the duplicates are documented as having been pushed around 11pm by my iPhone. Both my Windows and Linux machines were fully shut down.
I unfortunately don’t have sync logs of the iPhone’s 11pm push (unless there’s a way to see historic sync logs that I’m not aware of), but there is a version history entry for the issue.
It was simple to revert, but this is a fairly consistent issue I’ve had for months and it’s begun to make me uneasy as I’m not sure where this duplication has happened in other files I haven’t checked recently.
Other than this issue, sync is perfect for me. Let me know if there’s any additional info I can provide.