Weird mana and cast speed problem (bug?)

I encountered a strange phenomenon while mapping: when I had 4.74 cast speed, my mana started to disappear quickly. When I reduced the cast speed by 2%, the mana issue was resolved, and similarly, when I increased the cast speed by a few percent, the problem also went away. I tested this on a friend's character who plays the same build, and he noticed similar mana issues when his cast speed was at 4.74.


Here's a video of it
https://packaged-media.redd.it/l8n68pfrgp6e1/pb/m2-res_1080p.mp4?m=DASHPlaylist.mpd&v=1&e=1734152400&s=725623461c23788e93bd32b68e11091ceeba1847&x-auth-token=eyJhbGciOiJIUzI1NiIsImtpZCI6InNPQ1JhUkNOTkZnL3Y3NkFRWVdYUkJhYWJ4QT0iLCJ0eXAiOiJKV1QifQ.eyJjYyI6IlBMIiwiY3IiOiIiLCJleHAiOjE3MzQxNTc0NDYsImp0aSI6IiIsInJpZCI6InQzXzFoZHE0dDciLCJzdWIiOiJ0Ml9razV2d29wbCIsInVybCI6Imw4bjY4cGZyZ3A2ZTEifQ.Dp1IP8Qmb41G8Z5Wj56EkDlTltfWLdbo_bmZ2_fbSNE

Bump, I just encountered this bug at 7 to 7.10 cast speed