I think Mario summarises his frustrations in great detail here: Using toolbox with Big Sur and M1 MacBook? - #18 by matt_j_dunn
If anyone can gain access to a graphics engineer at WWDC, this would be a useful place to direct them, though some of the invective probably won’t induce someone who doesn’t appreciate a challenge…
Like others in that thread, I am working towards using a Linux machine (considering a RPi 4 with Octave) as dedicated hardware for stimulus presentation, communicating with my experiment-control machine. Fortunately in my case, I do not have a critical need for high-precision graphics timing, so I really haven’t gone all-in yet.