AFAIK The current version of Bitcoin core cannot sign any SegWit address.
Only Electrum and other 3rd party wallets can sign a message in a "nonstandard" way.
Means whenever the SegWit-signable update came, those signed message through Electrum can be invalid to the new standard method.
..
It is widely known in the "
Stake your Bitcoin Address" Thread.
I don't think this is widely known in the "
Stake your Bitcoin Address" Thread.
Just as Sellingaccs didn't knew about it, a great part of users here doesn't know.
People are making signed messages using electrum, but they cannot be verified using any other wallet, and the method used is non-standard. I doubt more than 10% of the users in that thread know that.
I agree with the OP, electrum should advert users about it. But I doubt they will change it, and probably even when Core make a standard signature verification Electrum will keep its own verification method, just like BIP 39, as they use a completely different method to generate the recovery phrase.