Icon Hide & Seek

Since BS (Big Sur), my icons do not stay in the dock. I do select Keep in Dock and assign to all Desktops. But I reboot and many icons are missing. I also find icons missing from the menu bar such as mirroring or volume. The ones that do seem to stay are not in the sequence I've had them in.

Icont figure out why.

Curiously I see two instances of FireFox icons on my deck, one on each side of the line.

Also in the disappearing arena.....in finder, I don't have "recent" or "all."