- does the wallet-backup of Electrum contain the seed too?
If you are asking this because you're thinking that you don't have to back up the seed phrase if you have a copy of the wallet file and the password, then please reconsider this.
When you created the wallet, you should have already devised a backup strategy for storing the seed phrase so you don't lose it.
From a data recovery point of view, inside the wallet file is
not a safe place to leave the seed in by itself because there are so many ways for a wallet file to get corrupted.