I use my iPad Pro as a tablet with apps like Easy Canvas and Duet Display, and I have never had any issues until I installed 2021.
Using the Apple pencil on the Move, Scroll, Zoom, and Rotate buttons does not work anymore. The only button that responds is zoom, but it only responds to tapping for small zoom increments (only zooming in).
The problem is reproducible across both Easy Canvas and Duet Display. These functions all still work fine in the viewport navigation (drag for rotate, hold alt to Scroll, release alt to zoom).
Hope this info helps!