I have a DIY CO2 laser running on GRBL-ESP32, which is terrific BTW.
I have issues when cutting with the M4 command as corners sometimes don’t cut due to the variable power using M4. I found a post from around 12 months ago which Oz answered but is now closed:-
There isn’t a good way to fix this with GRBL unfortunately. The only real option is to use the GRBL-M3 profile in LightBurn (constant power mode) for cutting. We have an update coming that will allow you to choose M3 (constant) or M4 (variable) power per layer, which would help, but ultimately standard GRBL doesn’t work well for glass tube CO2 lasers.
Did this feature make it to a release?