I know that the pibrella board is not sold anymore, but I still have one and just needed the buzzer for a quick test.
In the node-red-node-pibrella doc I can read the following:
## Pre-reqs
Requires the RPi.PIO python library version 0.5.8 (or better) in order to work. See the [RPi.GPIO site](https://pypi.python.org/pypi/RPi.GPIO) for mode details.
sudo apt-get -y install python-rpi.gpio
but my Raspian Bullseye tells me:
Package python-rpi.gpio is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
Nevertheless I installed the node, and the Palette says:
Warning : Can't find RPi.GPIO python library.
How can I install a RPi.GPIO python library for Bullseye?
That node is liable to very old and prob rely on Python2
[edit] I just looked at the pibrella node and it is maintained by Nick and Dave so maybe it might get updated to work nowadays[/edit]
Workaround could be to just use the standard Pi output node to make it beep
Just tried the pibrella node out on my bullseye and I get the same error message in the console as you which is strange as RPi.GPIO is definitely installed