Yup. Looks like a bug. For sure because Apple made the knob larger (sounds like a bad joke). And it’s also in the built app.
Do you know how to do a Feedback issue?
There are a few canvas based sliders around. For instance, this here: https://1drv.ms/u/s!AjJkpl3iB1f_hlt58JXaD_IfGzg3?e=4d72wk