>>56232005I feel like I've said this five times now, but here we go once more:
From what we can tell, Niantic drastically increased their spawn rate after the biomes update. This was presumably done not just because of lake biomes but also because we're past Sinnoh Tour at this point in the game's FOMO life cycle, so they don't really see any need in keeping the lake guardians as rare as they normally were.