Cursor-down not working 100% on a end-of-2019 MacBook Pro
This sounds like a typical symptom of the butterfly keyboard.

your Mac is less than a year old and should be covered under nornal warranty.
It may be covered under the Keyboard Service Program

Both the 13” and 15” MacBook Pro laptops are covered under the program.  I wouldn’t  attempt a fix as any damage may nullify your coverage.  Just take it in.