I have a m1 MacBook Air.
I've found the following things fix the error:
1. just try launching again a couple of times. sometimes it goes away on its own.
2. switch to a lower version of forge.
3. Switch to a higher version of forge.
4. add the -Dfml.earlyprogresswindow=false argument
One of those always works for me. Note I am not a code person and this is just from Trial and Error XD