It is a pity that this will not help me or the users of the wallet in any way - it means that there will still be the same leaks from the wallets of other owners.
You still don't seem to understand. Electrum happens to be one of the most widely used desktop wallets, along with Bitcoin Core, and has a vast user base of millions of individuals worldwide who utilize it at any given moment. It's highly unlikely that any security vulnerabilities within the software would go unnoticed, given the sheer volume of users and the attention that such flaws would attract online. I'm not saying it's impossible, just very unlikely. So, rather than making baseless accusations, it would be more constructive to provide evidence to support your claims.
About 3rd party... I mean somebody did this without hacking my PC. I don't know how it could be done and it's looks imposible for me too.
Electrum is open-source software. Feel free to review the code yourself and report any loopholes or vulnerabilities you find.
But above I wrote why I think that access to my PC at the time of the specified date would not have given anything even if it had happened
After reading your explanation, I must say that I have serious concerns regarding your OPSEC and its effectiveness. Deleting your wallet profile after each use provide no significant protection, as it offers no real advantage in terms of security, unless you used an offline, air-gapped device to sign your transactions. Similarly, there is little advantage to adding another password to the archive since the wallet file's encryption already provides an adequate level of protection and is virtually impossible to break.