console: no USB keyboard!

Running 14-CURRENT on several boxes (i.e. FreeBSD 14.0-CURRENT #49
main-n245422-cecfaf9bede9: Fri Mar 12 16:08:09 CET 2021 amd64) with custom and/or GENERIC
kernel and USB-only equipment (mouse if available, keyboard).
In multiuser mode, there is no problem using the USB keyboard. On single user console
(for maintenance purposes), no USB keyboard is available. The same is true while booting
and the rc scripts are worked on. Usually, one can hit the enter key and inserts a
newline, this doesn't work anymore until the box is completely up! 

I do not know when this problem as been introduced, the very same config is used since
13-CURRENT in its earlier time and has been modified accordingly, but I can't see obvios
changes which would explain the wrecked behaviour now. 

I got aware of this problem, when a small mistake in /etc/fstab rendered a box
unbootable, I had to head for the datacenter and wasn't even capable of interrupting the
stuck system. Checking on other boxes running recent 14-CURRENT revealed the same problem.

The interesting part is, that as long as those boxes are with the loader present (all
boxes are UEFI booting!), the USB keyboard works as expected and I'm able to select
kernel/kernel.old and so on.

How to fix this?

Thanks in advance and kind regards,

O. Hartmann