If this fix is going to change the way levels are being generated, does it mean existing seeds will be changed too?

Each big version the amount of things changed makes the old seeds obsolete anyway. Maintaining the seed "feel" between versions was never a goal for us.

That said it is fairly stable, as we first generate sub-seeds for levels and then run the generators using that seed.

Ok. Thank you.

very cool thanks for the reply, I didn't know if this was old news or not, and it's actually the first time I've managed to get this to happen in any run.

the only other major glitch I've noticed is enemies sometimes spawning outside of the gameplay area, but that seems to not really happen on haste trials at all.