I added a copy of the GRBL Library machine to my workshop, no changes to any settings, everything is default. When I download the sheet, this is what the first two lines look like, exactly:
asdf; Generated by Fabber
; Thu Jan 20 16:04:41 UTC 2022
Other machines aren’t doing this for me. It’s not a blocker because I can just delete those 4 characters myself, but clearly this isn’t expected behavior.