RCV encourages moderation, meaning candidates like Peltola and Senator Murkowski (R) win statewide office. This distresses people who feel like such moderates are very far from their own views.
Simplicity is an underrated value when it comes to elections. People are more likely to trust that which they can easily understand. And ranked choice, fairly or not tends to cause a lot of confusion.
It pisses off people who don’t understand compromise.
But they know they live in a state where any presidential candidate with (R) next to their name can win by 10-20 points. So they wonder how such a state can elect a Democrat without something underhanded going on. A working theory is that the RCV system is "too confusing" for some folks and it leads to the D candidate winning an "undeserved" victory.
IRV, though imperfect, is so clearly superior to one candidate voting if the goal is a responsive democracy. Unfortunately, there are many people who don't want that. IRV closes a loophole for extreme candidates (I have a strong suspicion that the 2016 djt campaign would have been thwarted by IRV had the gop primary used it). It also allows partially aligned challengers to pressure incumbents without dividing the electorate. This would likely be better for the challenger and the incumbent. Consider this past election where Jill Stein was demonized as a spoiler, which she potentially was, but would not have been in ranked choice. I bet there are a lot of voters who would have rather voted for Jill Stein but instead cast their vote for a candidate whom they thought could win (including candidates who received what should have been Jill Stein votes and thus lost important information about what matters to their voters). This is bad for everyone except those who don't believe in responsive democracy and largely rewards career politicians, political consultants and lobbyists.