To clarify, do you mean you are one-way copying your vault to Google Drive and OneDrive?
Because otherwise if you are editing/syncing your Obsidian Synced vault in a live cloud folder, even if the files are not visibly conflicted, they might be overwriting each other.
I would triple check you don’t have any mixing sync tools. And if you are certain you don’t, I guess the next thing to check is the standard debugging steps:
And perhaps post your “Show Debug Info” to see if there are any plugins people recognize that could be causing the trouble.