This has been in the game for a while and i've been using it regularly so i have no clue why haven't i reprted that one, mayb3 because I thought it's such a small window that it requires high skill? You can decide for yourself. In some of my recorded runs you can see it, for example ~3:38 in my void fragments run. Basically, after pulling a spear/leaver there is a small window you can move before your extra turn start if you time your keypresses right. With the. Ability to pull this of consistently you can preaty much use spear point-blank, pull it and before next turn get close enough to go infinite with next spear. I like skill based bugs like that so I'd love it to stay but it's not 4 me to decide.
#spear/cleaver shenanigans
sharp hill
hard geyser
I don't know if I'd consider this a bug, more of just it's how the game works with movement and the iframes between turns. I also use this mechanic myself too. There are a few others where you can get a slight amount of movement between turns to just reposition yourself a little bit