I activated Radeon Boost and it was working in PUBG. I saw the small green square in the top left corner. When I tried moving my mouse the dynamic resolution was clearly activating (even in the game lobby).
When the dynamic resolution was occurring you could see the number of squares in the top left would increase from one to four.
However, I switched my monitor from Freesync On to Off, and tried to turn on motion blur reduction. I had a rare blue screen strange crash.
When I load PUBG now: I get a single green square in the top left but no movement detection. I also cannot see any obvious dynamic resolution reduction.
How do I fix Radeon Boost in PUBG? I tried a clean re-install of the 20.4.1 drivers. This didn't fix it.