Hetzner's server console "dead" after upgrade from 14.3-STABLE to 15-CURRENT

Hi

I upgraded one of my servers from 14.3-STABLE (arm64) to 15-CURRENT (arm64), recently.

Ever since I cannot use Hetzner's server console to login that specific cloud instance any longer.

I am able to connect to that instance and I can watch it boot and presenting the login prompt on ttyv1. But I am not able to login, because the console is "dead" w.r.t. keystrokes.

After reading UPDATING and RELNOTES I cannot see a possible cause for that changed behaviour. At least it is not obvious to me.

I have to admit that I am completely lost here, and I do not even know where to look for solving this issue (ttyv0, keyboard, …)

Questions:

#) Is anyone using Hetzner's server console on 15-CURRENT (arm64) successfully?

#) What has changed between 14.3-STABLE and 15-CURRENT I have overseen?

#) Hints for investigating/debugging this issue?


Thanks in advance and regards,
Michael