Betta Glass Surfing and Flairing at Reflection

We just moved our month owned betta to a 5 gallon glass tank from a 2.5 gallon plastic tank. He has been attacking the glass and flairing pretty much non stop since the move (3 days ago) I assume because of the reflection. we have since removed all tank lights, tried putting a darker background and lighting coming from the room itself instead of the tank and he has plenty of hiding spots. Still he is attacking the glass to the point I am worried he is way over stressed, or will hurt himself.

Have y'all dealt with this? How should I go about reducing the reflection or calming him down?

Thank you all!