my monitor is a bit darker than most i think because i have the brightness lowered pretty far down due to personal light sensitivity, Which in most games i fix by bumping up their brightness / contrast settings if i need them and its fair that your game jam game doesn't have those options. As for the red thing, honestly I can't recreate it now, I think it was when I took "damage" by letting a flower die but If I remember correctly it staying red after for the rest of the minigame after.