Alexandre Colucci:

The version 66.0 was a 165 MB app on an iPad Air 2 (64-bit). It was a monolithic app with its main binary being more than 100 MB.

The version 87.0 is now available: 253 MB on the same iPad Air 2 with only 64-bit code. In just 6 months, the Facebook.app size grew by 88 MB!