It just felt like you get punished for playing tetris well. You should be able to overcome the enemy with tetris skill like clearing fast and not making gaps.
I like tetris challenges, like floating pieces and digging through garbage, bomb. The weird shapes seemed like a fair challenge because the player still had agency to overcome it with placement.
Instead of randomly flipping the piece, which felt buggy, what if the piece was locked from flipping or something. The invincible timing, was ok since you can stall the line clears.