Hostile mobs not spawning in the new snapshot

Was recently playing in the new 25w02a snapshot in a hardcore world and hostile mobs wont naturally spawn, only via mob spawners (from what i have found) but in caves or during night they dont spawn at all, only passive mobs. Another strange thing was when i was recording, whenever i type "a" in the chat it just deletes all of my previous letters typed. Is this supposed to be happening or just bugs with the new snapshot?