The spell find familiar allows a character to summon a familiar, which is a spirit of creature type celestial, fey or fiend. From the spell's description (PHB, p. 240):
You gain the service of a familiar, a spirit that takes the form of an animal [...] the familiar has the statistics of the chosen form, though it is a celestial, fey, or fiend (your choice) instead of a beast.
Would there be any balance issues with allowing the familiar to be of the elemental creature type instead (meaning, adjusting the above description to read "celestial, elemental, fey, or fiend (your choice)" instead)?
Elemental creatures are affected in the same way as celestial/fey/fiend creatures by other spells such as protection from evil and good, forbiddance, and banishment (being permanently banished to their home plane rather than just stuck in a demiplane for 1 minute), etc, so being an elemental shouldn't allow the creature to bypass that which would affect a RAW find familiar familiar.
That would have been the main thing that I would suspect might affect balance, but I can't think of a spell that affects only celestials, fiends and fey, but not elementals. And I don't feel like the concept of an elemental spirit creature being summoned as a familiar goes against the narrative theme of the spell either.
Are there any odd interactions with an elemental familiar that might make it more or less powerful than, say, a celestial familiar? My intention is for this to not affect the balance whatsoever.
