Things happened
Briefly speaking:
I bought Ob-sync →
My computer’s disk broke →
I tried to recover my notes from my Iphone => I set up and sync with a new vault (as I forget the previous password). →
Only a small part of data were successfully synced to the computer => it synced back (from PC to remote) and deleted most of the files in the remoted vault => then sync from remoted vault to iphone and deleted the files in Iphone.
PS:
I’ll post this in the Help also.
There is a topic Sync stopped working and then deleted over half my vault - Help - Obsidian Forum where the author meet a situation kind alike, but with no reply.