All of the colored characters in The Rings of Power should have been white because there are no explicitly stated colored characters throughout The Lord of the Rings canon, meaning a race cleansing would have had to have taken place at some point in the middle. Good characters? For sure, but this isn't necessarily a racism issue so much as it's a continuity issue with J.R.R. Tolkien's races of characters (elves, dwarves, hobbits, et cetera).
here's the thing though. as a tolkienverse fan, i think full continuity is impossible. i don't expect every character and sideplot can make it into a film/television adaptation, largely because film is just a different medium than text, one where relatively simpler stories are often more successful and impactful. i wasn't upset when tom bombadil didn't make it in the peter jackson movies, and i think it'd be pretty silly if thranduil was only called "elvenking" in his hobbit movies.
if a fan (not saying this is you, just "some fan") knows full continuity is impossible, yet they specifically object to race discontinuity, and not anything else, what does that tell us? likely either they have some kind of hangup about race, and/or the story / our societal understanding of it are structured such that making someone non-white jumps out as "strange", in a tale where the volcanic dark lord binds part of his soul into jewelry. which feels a bit odd at first blush.
another way to think about this general topic is what i call "the viking question." which of these images has more continuity from real vikings–the spotless guy on the left with the widely-debunked horned helmet, perfectly shiny double-bladed axe, framed by the sun just so... or this guy on the right with signs of injury and grime, a simpler axe with more wear, a mail shirt, and some furs, who also happens to be black? i'm not saying the guy on the right is a flawless depiction of historical vikings, he's not, but to me, he has considerably more continuity than the guy on the left. if someone reading this thinks the guy on the left is more realistic, i do not mean to say you're a racist. just that you, like everyone including myself, should remember that perceptions of "having continuity" / "authentic" / "realistic" are sometimes not grounded in the facts.
Whether or not they're better movies than the previous films is up for debate, but everyone throwing hate at the Star Wars sequel trilogy these days is going to look like a massive, massive idiot when another trilogy of movies ever ends up happening. We've seen this with both of the previous trilogies- when the prequels came out, people hated them and loved the originals, but when the sequels came out, people hated the sequels and loved the prequels all of a sudden.
This is more a partial disagree than a full disagree, but my view is like... people throwing hate at the prequels don't look like idiots, even though another trilogy came out after the prequels. Because the prequels are bad. (That doesn't mean they lack all merit and likability though, of course.) I think some
of the people throwing hate at the New Trilogy look foolish because they only
condemn the New Trilogy, e.g. inflating the prequels on a lofty pedestal they really don't deserve, but I think a fair portion of legitimate criticism and hostility will be well-vindicated by history.