Start clean by force-quitting Touch Bar services: open Activity Monitor, search for and force-quit TouchBarServer, ControlStrip, and Touch Bar Agent, then tap the Touch Bar to let macOS auto-restart them.
If that doesn’t help, head to System Settings > Keyboard, choose Expanded Control Strip, then Customise, and drag everything off the bar, sometimes keeping it empty stops the flashing entirely.
Another thing to try: go to System Settings > Displays and turn off Automatically adjust brightness, since the ambient light sensor can misbehave and trigger flickering.
If none of this works, it’s likely a hardware issue, especially if it started after a macOS update or following sleep/wake, and might require top-case or Touch Bar replacement.