This bug started occurring in 21.1.1 I think and still occurs in 21.1.2. Only occurs when using a tablet.
When holding 'ALT' whilst lasso tool is selected (in order to temporarily toggle polygonal lasso tool) there is about a one second 'window' between presses on the canvas where PS registers all the movement of the pen between clicks and counts it as 'lasso' input, despite the ALT 'toggle' being active and pen not in contact with tablet.
Normal behaviour should be that PS only records the movement when pen is touching tablet.
I draw 2 circles with the lasso tool then I draw a new selection with 'ALT' held down. I am lifting the pen inbetween presses and always have ALT held to keep the tool in polygon lasso mode...you will see it does not behave as expected and the selection has a second where it registeres movement despite the pen hovering above the wacom.
I then select the polygon lasso too as primary tool (not with ALT) to show you that it works fine if used as primary tool.
This leads me to believe that it is an Adobe PS problem.
Running Win10 pro 64bit with latest drivers and software, Wacom Intuos Pro L.