Really not convinced that you can’t call something a genre because it wouldn’t describe different games in a series.
I’d argue the Wario Land series has mostly changed genres between 1 and 2. First one is a straight platformer that’s basically Super Mario Bros with different abilities, following games are exploration puzzle game things that have a platforming element, but in which platforming is not the main point IMO.
Resident Evil really forgot it was survival horror for a while.
Breath of the Wild/Tears of the Kingdom are almost nothing like the classic Zelda formula. Free-form puzzle solving, free-er movement, almost zero dungeon structures, consumable weapons…
Those are significant, because when it happens it’s very likely some people would be more invested in either the old or new games, which incidentally explains why it doesn’t happen that much in established series.
I know I was initially very disappointed with new Wario, because all I wanted back then was more Mario-style platforming and the intentionally frustrating design of Wario Land 2-3-4 wasn’t for me.