When putting film on make sure the lens is as clean as possible, and apply it with a little very mild fairy water misted onto the film and lens.
Then squigee it out, this will give the clearest view / best bond
I know people worry, and it’s understandable with replica optics but don’t forget that the likes of Eotech etc are ballistics rated and will take ridiculous punishment, like 2M drops with the full weight of the gun above it - and keep zero, let alone not cracking the lens etc!