COD doesn't use typical SBMM by definition - that's just the basic term coined by users when they are hit by it. The games use EOMM and SBMM concepts. If the games used traditional SBMM like seen in many other competitive titles then every lobby would be painfully streamlined based on current skill but COD has retention-based factors (EOMM-driven) in play where you get buttfucked for a couple of games let's say, and then you can rest your ass with an easy match after, which baits you into playing more rinse and repeat. Lobbies disband and the back-end algorithms are desperately working and then there's instances where your connection may be manipulated or guns suddenly don't feel as effective. It's all phycological and artificial - you will have a great game but expect to also get battered in the same session especially if you are playing solo. COD games are scripted just as hard as FIFA and it's more obvious than ever.
If people want a fair experience then a game like CS2 is the way to go - no P2W bundles, sub-tick servers, clean netcode etc. but games like COD are rigged to a degree and punishment always drives retention especially when Activision can flaunt their temporary P2W bundles as leverage. I remember playing Cold War where EOMM was so predictable, I could tell before a match exactly how it would go! COD should either use pure SBMM or exclusive connection-based matchmaking. This current EOMM-based monetised-matchmaking is just too much of a strain on the community especially if in-match factors are also impacting.