As is, it's very easy to lock yourself out as it's enabled in a single step without checking that it works before saving.
The good news is it's being worked on:
https://github.com/LemmyNet/lemmy/pull/3959 https://github.com/LemmyNet/lemmy/issues/3309

So, eventually, your situation will be much less likely to happen.
For now though, I think your only hope is to reach @TheDude@sh.itjust.works (insert R2D2 holo of princess Leia pleading to Kenobi)

DMs on Lemmy being insecure, you're probably better off dealing with this through Matrix.
https://matrix.to/#/@thedude.itjustworks:matrix.org

Maybe don't trust a link from a random stranger (me), you can find the link to his Matrix account by clicking on "Send Secure Message" on his lemmy profile.

Good luck

Hi there

Sent you a message on the matrix chat. This should now be fixed.

Thank you