I click on villain titled books because I like a good redemption story or seeing someone dig themselves out of holes, but often I find that the "villain" in question isn't actually bad: via a) misunderstood/framed b) transmigrated/got prophecy BEFORE their villainy timeline so they avoid in advance c) villain by circumstance (not on hero's team) but not by character... Bores me to tears and i feel cheated.
I think it happens because authors who like a genre copy the broad strokes without actually thinking about it. Like there was an original villain redemption novel they were inspired by but they didn't copy the development that made it interesting. So now there's more fake villain novels than actual villain novels. It seems to happen with a ton of subgenres. I've seen it in villainess novels, isekai novels, kicked out of party novels, system novels...etc.