A couple of deleted scenes have hit the web in advance of the home release.
I kind of wish they had kept the quantum realm scene. It adds a little more texture to Janet's experiences there, rather than just make it getting it seem like she had been standing there waiting for Hank to show up for 30 years.
The security camera scene - Yeah, I get why it was cut.
The Quantum Realm bit - Sorry but i don't think that scene was either overlong, or boring; and as others said, it adds depth to the QR, so IDK why it was cut. Especially with Ant man now trapped there. <--- Of course perhaps that IS why (IE They wanted to save the 'reveal' of civilizations in that realm for Avengers 4.)