A followup to my reply #4 above.
I booted my MacBook Pro 14" (m1pro) to Tahoe, and checked Passwords settings again.
It STILL does not present any option to "show excluded websites".
So... my guess is that you will only see this option in Passwords... when you have already used the "never save" option in Safari.
I don't recall ever making that choice, so... I don't see it.