When adding a new instance of ReaEQ to a track, its window is too small to fit it. After simply closing the window and reopening it, the window is the proper size. It's kind of annoying given how often I use ReaEQ. Not the end of the world though.
It's a bit hard to describe in text, so
here is a screen recording.
Reaper 6.25.
HiDPI mode is "Multimonitor aware (recommended)". In Windows, my display scale is set to 200%.