A simple but less-than-ideal workaround (which I ended up doing, but can't reasonably recommend for security reasons) is to uninstall Firefox altogether, and reinstall it from a 145.0.2 APK (the last one still having "Share all tabs" afaik).
I guess the update landed in the stable version recently: my FF auto-updated a few days ago and, lo and behold, "Share all tabs" was gone. I found that so frustrating.I guess there are always trade-offs, choices to be made when you're making your pro...
