I have clearly demonstrated the sonic effects of this to others in my listening room.
1) User a cleaner to remove the film. AudioTop is expensive but works really well. Clean the disk twice.
2) Use a black permanent marker on the edge. Black blocks all light. People started using green because it cancels the stray red laser. Black is better.
Then Marigo makes mats to place on the disc. I used 6 different mats over the years. The latest Marigo clear mat is by far the best. the other mats just removed glare and improved focus. This Marigo clear mat seems more like a player upgrade.
There is more. But start here.