That is a first for me. Never heard of that issue before.
Hmm, maybe try this. My /e/ only goes up to Pie so not sure if the info will apply.
Go to Settings → Trust → Privacy Guard.
Find Firefox and long-press on it. You’ll see a list of permissions(?) or appops. See if there’s anything there that may relate. Is there a “Start at power up” entry. If so it probably doesn’t have a toggle. Long-press on it and you may see options similar to…
Select “Ignored” and see what happens.
Otherwise, have no clue about this one.