I have similar question raised in another part of the forum, posting the link here for information. [question] how to avoid double sync on mobile? - Help - Obsidian Forum
My conclusion is that I shall continue to use Obsidian Sync but have to give up storing the vault in iCloud (or other Cloud services such as dropbox, Google Drive, etc). This means each device has to have a local vault placed on them but I prefer Obsidian Sync due to the additional features it brings, especially that I can use my own strong password for E2EE
Hope this helps