https://www.pcgamer.com/black-ops-4-players-unhappy-with-20hz-tickrate-treyarch-says-improvements-are-coming/

Call of Duty: Black Ops 4 is predictably good—cautious, but polished to a brilliant corporate sheen, as we said in our 78/100 review—but analysis by redditor Smcro indicating that it runs with a surprisingly low 20hz tickrate has not gone over well with players.   

"Battle(non)sense made a video back in August concerning the multiplayer beta where he showed that both the client and server send rates were ~60hz (i.e. each send 60 updates per second) for multiplayer. However, my testing for the most-recent update (as of October 19th) shows that the server send rate has been cut down to 20hz," Smcro wrote.