I'm seeing the same thing on my end as the OP. I assumed someone else would've reported it by now so I didn't even think to jump on here and report it.

It seems to affect me the most when I'm in a city setting and performance starts to suffer. It acts like the input/polling rate from the mouse dips along with the framerate.

When I first noticed it, I thought I might've inadvertently turned down my mouse sensitivity while opening doors but I actually hadn't.

I too have a Logitech gaming mouse (g500s), but I can't imagine it's related to that.

duplicate of 12774

This appears broken again on the experimental pushed today.

Mosin is all over the place. Laying down, crouched or standings straight up results in the exact same amount of sway.