The Pressure setting in the Settings panel dictates both how deep into the canvas media is pushed and the max width the tool head can “splay out” when using a soft headed tool like an Oil brush.
The cursor, when in Outline mode, will indicate an estimate of this potential max width of a stroke.
Theoretically at 100% the head should be at its widest but in practice when using a pressure sensitive tablet there is still a little leeway for the head to expand & contract slightly.

Regarding the first screenshot, I can’t reproduce those tapering strokes that you have got when trying either of the settings you show in your two screenshots And nor would I expect to!
A possibility though, if your tablet’s preferences allow you to edit it’s pressure curve, is that your tablet’s pressure settings may be unduly influencing ARV?
But if that were true, then I would have expected to see very similar results in the second screenshot too? So it may not be that…?
If you restart ARV and/or the computer dose the brush still respond in the same way when using the settings as seen in the first screenshot?
I’m wondering if perhaps ARV has just got a bit “confused” when making those blue strokes? (Yes, I know I’m clutching at straws here!)