It seems that Treyarch upped Call of Duty: Black Ops 4's server tick rates to 62Hz and while Blackout still runs at 20Hz, the game's standard multiplayer plays way smoother. Of course, with such changes, you need to know what to look for.
Reddit user called soja92 was the first one to report this, having tested it in the Northeast part of the US, although it seems like it's the same everywhere. He tested it both on PC and PlayStation 4 version, both of which run at 62Hz in multiplayer and 20Hz in Blackout.
He also watched out for any dynamic changes, just to make sure Treyarch didn't choose to increase Call of Duty: Black Ops 4's tick rates as player count decreases but that's not the case. Coincidentally, someone mentioned that PUBG uses dynamic tick rates although our recent experiences with Desync Unknown wouldn't suggest it.
Now, it's a common thing among game developers to use lower server tick rates at launch, which lightens their load significantly while they figure out how big is the horde. Call of Duty: Black Ops 4 Blackout matches are quite a busy affair so it's understandable that's it's lagging behind at the moment, but it should get better soon.
Treyarch said earlier that they're aware of the discussion regarding Call of Duty: Black Ops 4's network performance and announced a bunch of changes to their "network setup" in this and the following week. One thing is for certain though - if Treyarch and Beenox keep up this tempo, they just might achieve the feat of the best supported CoD title as of yet.
In case you're not tech savvy, worry not, because you don't really need math if you know what you're looking for - 62Hz means for more frequent communication between the server and your gaming device, providing a smoother and arguably fair experience. Unless of course you suck and you think that's the sole reason, which it rarely ends up being.
You can find the Reddit post in question here.