My work laptop is a mbp 2018 (i9, 32GB). The battery life is abysmal. I typically get a little bit over 2 hours. I'm not going to lie though: I'm always running Atom or VSCode and there's lots of opened tabs in Chrome.
Chrome used to half my battery life on a MacBook Pro. On a brand new machine with a full battery I could program all day in Xcode if I forgot my charger until one day it was empty halfway the day. Finally I figured out it was Chrome that killed it so fast.
Did they reduce the battery size on newer models? My 2015 i7 mbp can get about 3 hours of Civ 6 (in strategic view), or 6 hours of regular dev workload. I remember it lasting longer a few years ago too.
Yes. The previous generation 15" MacBook Pro has a 99.5Wh battery. The 2016 & 2017 15" touchbar MacBook Pro has a 76Wh battery. The 2018 model was upgraded to 83.6Wh. Depending on which version you have, you get either 15% or 25% less battery than the older model.
Yes. Can't remember how much it shrank in Wh though. I had a 2016 which I ultimately sold after 6 months, then bought a 2015 of eBay. I get roughly 25-33% better battery life on the 2015 than I did with the newer model.