Im curios how safe is currently the 12 mnemonic seed phase for example of of electrum 12 words against bruteforce?
The chance of someone to bruteforce 12 word seed phrase is very tiny, as long as all the words are unknown. It is when like 8 words are known, and some letters in the other four words are known that the it might be bruteforce. So you have nothing to fear about anyone being able to bruteforce your seed phrase.
i have some wallets with 12 seeds and im a bit uncertain if its really safe
It is safe as long as you keep it away from third party.