basically, I have the same problem as the person who created this discussion in 2016: Problem with Cs6 wacom tablet but instead of the pen being the problem, it's my brush.
their answer was to disable rubberbanding:
but there isn't an option for the brush setting.
no it isn't my tablet or its drivers, as it works completely fine on other programs (csp and pt sai)
this has been driving me mad and I couldn't find a resolution to this anywhere online. thanks.