The real question isn't whether the Mark II is better - it obviously is - but whether those improvements solve problems you actually have right now. If your R5 is nailing your wedding shots and you're happy with the results, the autofocus bump and extra fps probably won't change your life. Gear upgrades matter most when you're hitting the limits of what you've got. Are you missing shots because autofocus is hunting? Are you frustrated with burst speed? If not, you've got gear fever.
That said, the autofocus on the Mark II is genuinely better for fast-moving subjects and eye-tracking, and wedding photographers do appreciate the extra frames per second when things get chaotic. The question is whether you'd actually *use* those advantages or just feel good about having them. Three years in, your R5 is still totally capable. If you're not actively frustrated during shoots, I'd sit tight. Your money's probably better spent on lenses or a really nice backup body if you don't have one already.
If you're curious, rent a Mark II for a wedding or two and see if you actually notice the difference in your final images. Bet you find out real quick whether it's a need or just wanting the new thing.