Something that seems to be an increasing trend is to label everything Other as 'sidhe' whether or not it is or even whether it makes sense to call it that. Which is, quite frankly, very odd given that the English language has at least two generic terms - elf and fairy - for Other beings that have been in use for over 1000 years and 700 years respectively. So stealing borrowing one from the Irish language is unnecessary, yet here we are. Perhaps its because English speakers have chosen to radically minimize and disempower the words elf and fairy, reducing the beings associated with them into cookie bakers/shoe makers or twee little pre-pubescent children with gauzy wings and glittery wands. Perhaps because it all just seems so much more magical if the term isn't in English.
Sidhe - properly Aos Sidhe or Daoine Sidhe [people of the Otherworldly Hills] - is not just an Irish language substitute for the English word fairy, a convenient shortcut away from the twee-ified English terms. And I mean that literally, because the Irish word* for fairy is sióg. But that isn't what people want. They want the mystery and the power of sidhe, the implication of something godlike.
Which is, of course, exactly what elf and fairy originally implied. But why do the work to redefine one's own terms when one can just take someone else's and make them mean whatever you want? The blunt answer is laziness. Its hard and slow (not in the fun way) to reshape a term - the witches who have worked to redefine the word witch in western civ cultures across the last 70 years can tell you all about that - and its easy to grab a new, foreign term instead.
Of course we have our theories as to why people are glomming on to sidhe, but no one is going to want to hear them. Because they involve nasty words like colonialism, and appropriation, and exotification. They're rooted in the same poisoned soil that made Irish folklore so very popular during the Victorian era. When your own folk beliefs and terms have become children's nursery themes then your eyes naturally drift to your neighbours who you see as less sophisticated and more in touch with (uncivilized) spirits. Much noble savage. So magical.
Who doesn't love a little primitivism, right? Especially with added magic sparkle.
Here's a novel idea - instead of taking another culture's term from another language and rewriting it for your own purposes, why not just rehab the terms you already have? They meant power and danger once, they can mean those things again. All it takes is people embracing the language they have to work with. How do you think they went from meaning 'powerful potentially helpful or dangerous spirits' to 'cute and probably needs human help' in the first place? People re-wrote the stories, re-wrote the meanings, and the associations with the terms changed. Change them back. Its possible and honestly its important. Reclaim the terms and reverse that diminishment. Empower instead of disempower. Give elves back their numinousness, give fairies back their danger.
Reject the Victorian propaganda that made these beings helpless - because they never actually became helpless, they were just unmoored from the language, lost to popular culture's consciousness.
Sidhe are very specific beings. They are rooted in a specific cultural belief. They have their own forms and ways and magics. Their own preferences and powers. Not every non-ordinary thing is of the sidhe. And, if we may be so bold, if it isn't at least a little bit dangerous, at least a little but frightening - doesn't bring a feeling of awe - then it isn't of the sidhe. Even in ordinary guises they are unnerving.
Honestly elves and fairies should be as well, because most of what gets labelled as an elf or a fairy also isn't, or isn't exactly, in the way they would have been understood before. As the terms were watered down and broadened they took in a range of other - or Other - beings who weren't deity adjacent, weren't subtly terrifying. And that's alright, better too broad than too narrow. Call it an elf or fairy if you must, because those have been generic terms for a very long time but before you jump to label the random, helpful, wants-to-be-your-new-bff-ascended-guide spirit you just met 'sidhe' maybe take a minute to find out if it actually is one of na Daoine Sidhe. And no, the spirit being okay with you calling it that doesn't mean that's what it is. It could let you call it Bob and that doesn't mean its name is really Bob.
And yes, its a sad day when there's an argument to use these words which have for centuries been avoided in favour of euphemisms. Words which the Good Folk don't enjoy hearing, which offend them - but what offends worse is being labelled as the wrong being entirely. Truth, in the end, is better than homogenization. And so, as I said at the start, here we are.
*Obviously there is no Irish word for this, but this is the word usually used in translation, representing roughly analogous concepts. emphasis on roughly.