You are probably suffering from the popup menu bug with this version, multiple screens, and different display scales per screen. The menus affected are Timeline, clip context menu, Keyframes, and Rich Text editor. Probably some of these combos are affected too. The fore-mentioned menus are fixed for the next version, but it is going to take a long time to update all of the rest of the UI to the new API where this works.
You can either move the Shotcut window to the other screen, disconnect screens, run Shotcut with command line argument --QT_SCALE_FACTOR 1, or downgrade.