I just had a weird experience with the Electrum mobile wallet as well...
The
default_wallet had the same "password" as my mobile device PIN?
... which I don't remember setting... as I only use the mobile app for "testing" and all the test wallets have the same password set.
After changing the wallet password back to the "standard" one that I use, I'm unable to replicate this issue... even after setting/unsetting the PIN code feature several times. I can only assume that I had actually set the password to be the PIN at some point?
Although I'm not sure why I would have done this...