I have updated from an older Nighlty to the "LibreELEC-RPi4.arm-11.0-nightly-20211028-a148fc2 "Since then my Auth Key is rejected.Did you change something?
The recent openssh update from 8.6p1 to 8.8p1 disables RSA signatures using the SHA-1 hash algorithm
by default. See "Potentially-incompatible changes" of https://www.openssh.com/releasenotes.html