There's a possibility that they are accusing you, but actually, it's them that are lagging. Jitter becomes a massive issue if you are playing people that are geographically a long way from you. A 300ms ping, plus 45ms of jitter is a game-ender. a 50mg ping, with 50ms of jitter, is almost irrelevant. They might be fine in other games, but when they play with you, there is an issue because you are further from them, and the jitter affects it more. I'm in Australia and if anyone has jitter, the game becomes unplayable. It's not my connection, it's theirs, but they don't see it like that.
It's also possible that it's your CPU. What CPU score do you get? Your CPU might be good, just not as good as everyone else's, so it becomes the bottleneck. There's also the possibility that your computer is doing something else, which is affecting the game. The game only uses a single core, so if there's another application using that core, it can make a huge difference if you are also doing something like watching YouTube, Mining crypto etc, then that eats resources.
Another possibility is that there was networking work being carried out. My current connection is 5Mb because my ISP is f**king around with it again. Some ISPs are amazing. In the UK Virgin Media was great but in Australia SuperLoop seem to mess with something on a weekly basis.