I would say that a creature categorized as fey does not necessarily have an origin plane of the feywild. My ancestors were from Scandinavian countries but I was not born there so I cannot be deported and would not be considered a citizen of the country my great grandparents came from. At least that's how I plan on running things.
I agree, and this is why I like the "home/native plane" wording Banishment used to have (and DIspel Evil and Good
still has), but now the paragraph for it is this:
"If the target is an Aberration, a Celestial, an Elemental, a Fey, or a Fiend, the target doesn’t return if the spell lasts for 1 minute. The target is instead transported to a random location on a plane (DM’s choice) associated with its creature type."
Extending your analogy, if "Scandinavian" was your creature type, it wouldn't matter where you were or how long you (or your family) have been there - 2024 Banishment would yeet you to a random location on the DM's choice of plane of Scandinavia (presumably the countries).
Compare the old wording:
"If the target is native to a different plane of existence than the one you’re on, the target is banished with a faint popping noise, returning to its home plane. If the spell ends before 1 minute has passed, the target reappears in the space it left or in the nearest unoccupied space if that space is occupied. Otherwise, the target doesn’t return."
Which is possibly too wordy (they don't like to give spells flavor like a popping noise RAW anymore, which I think were mechanically useful for spell identification and useful for DMs to inspire descriptions of their use and descriptions of other things, but whatever, it's not a hill I'd die on), but if the goal was to shorten it, "a plane (DM’s choice) associated with its creature type" is longer than, "its native plane (DM’s choice)." I like "(DM's choice)" being explicit here, but that's about it.
It really should have kept the "if the target is not native to the plane you're on" clause either way, because it's not even fixable by invoking a native plane anymore: even if the DM rules that the mindflayer BBEG's type of 'abberation' is 'associated with' the Prime Material enough to not be sent to the Far Realms, it doesn't negate the "random location" clause. This means a 4th level spell can still send the BBEG to a random location on the Prime Material, because they accidentally split the "random location" and "other plane" functions of the original spell by putting "DM's choice" after "a plane" instead of before the whole clause (e.g. "The target is instead transported to the DM's choice of a location on a plane associated with its creature type.")
This also means you can Banishment fey to a random location in the Feywild
while in the Feywild.
It is, in a word,
sloppy.
It really gives me the impression they weren't very careful with a lot of the changes they were making to shorten descriptions in 2024 rules.