What should we do? The only thing I can think of is to stay vocal about it. Never accept enshittification. Always point things out when they suck.
Focus on open protocols, simple formats over complex vendor-specific cruft. Then you can always "fork" away from an enshittified saas.
I bet a small team of the quality of the kind developers who are attracted to hacking on Ghostty could recreate the subset of GitHub functionality they actually need in ~six months. It's just the problem of how to pay for the ongoing care, maintenance and hosting? Maybe another opportunity for Mitchell's particular brand of philanthropic OSS.
Not selling out, basically. Easier said than done.