@humanetech @jollyrogue @lutindiscret
ok, so I followed instructions at https://www.omgubuntu.co.uk/2022/04/how-to-install-firefox-deb-apt-ubuntu-22-04 - took forever and it was, up to that point, painless to do. So I restart Firefox and ...
KDE Plasma crashes, I reboot, and now Firefox starts ... HOWEVER it isn't Firefox as I left it moments ago, it is Firefox as I left it last time I used the deb package, only with fresh imports of bookmarks. History is gone, tabs forgotten, not a big deal, but I do wish there'd been some warning.