@siky55: mine too, though I did found the extension's log under
Roaming\Opera Software\Opera GX Stable\Local Extension Settings\lcoemcffdmjaaomkchpjkmjfkljagidm
you will then find XXXXXX.log file, which you can open and see all the stuff you've ever written or deleted.
It might not restore all the missing data back to the note (I'm still figuring out how), but I find comfort in knowing that all my deleted data is still stored here, inside this jumbled mess.