After you’re hit from an enemy, your block input is ignored (same way as attack inputs) for a short duration (maybe 0.1s).
This results in chain-hits from enemies, most often seen from:
chaos spawn or ogre 3 hit combo. If you get hit at the start of it, you’re guaranteed to recieve one-two more hits, unless lucky.
horde, most often chaos hordes (due to very fast standing attacks). Make one mistake - be near hyperdensity and recieve one hit, and that’s it, get 3-4 more hits in a quick chain afterwards.
It feels a bit unfair: after you’re hit once, you can’t dodge (moveslow), and can’t do the most basic sort of defence - blocking. It’s frustrating when you know you can react to subsequent hits, but the game punishes you regardless.