Try the following. Taken from a suggestion for a different game on windows 10. It doesn't sound like a HUD issue if both dynhud and evohud do it.
For who wants a smoother experience with all the games I suggest to disable full screen optimiozation, usefull specially for streaming or if you wanto more fps (overwatch is just an example taken from the guide)
It's easy. If you want to disable fullscreen optimization for just overwatch, navigate to overwatch.exe, right click > properties > compatibility > check "disable fullscreen optimizations."
If you want to disable it for games across the board (which is what I did), go to your general Windows settings (windows key > type "settings" > gaming > game bar > "record clips, screenshots..." OFF > UNCHECK "show game bar when I play fullscreen games microsoft has verified").
Note that you have to turn the game bar off AND uncheck "show game bar when I play..." Just doing one doesn't fully disable the overlay.
Cliffnotes
Windows 10 has a "fullscreen optimization" setting that is enabled by default. It basically allows for overlays on fullscreen applications, mostly so they can put their game bar on there. It also allows for overlays of windows volume sliders and stuff. However, it seems to cause serious issues for many people, including myself (especially in overwatch).
Disabling the game bar is a common suggestion, but alone is not a fix, as the overlay is still there. You need to disable the actual "optimization" setting to truly disable everything.
I'd recommend trying it even if you aren't having specific issues. Disabling it seems to increase smoothness and decrease input lag. Also, in my case, it dramatically decreased GPU load for some reason.