in levels with Format=4 set, entering a new room causes spike blocks to use the collision of the previous room for 1 frame, which can let spike blocks with nothing above them veer off to the side, or let spike blocks directly below a tile clip into the tile slightly and be forced to move downward

this also applies to krusers (6:1); if a solid tile existed on the previous screen at the same height as the kruser with nothing but 2 rows of pixels at the very top, the kruser will collide with it and move down

however, these also add some interesting design possibilities; e.g. krusers that start by moving downward allow for more timing cycles with krusers, and spike blocks that start by randomly moving left or right can add more interesting movement patterns to spike block-heavy rooms. if this is fixed with something similar to HoloFix then i suggest adding four extra objects to bank 6: krusers that start by moving downward and gray/brown/white spike blocks that start by moving left or right