WF-1000XM5 Noise Cancellation

I've owned the xm4 for 3 years. The buds (silicone, purchased on amazon) fit absolutely perfectly.

On my MX5.. the buds I use for my XM4 do not fit (they're a small or medium). The large stock buds don't feel like they fit snug.

I know this is creating huge issues on the noise cancellation side. Did anyone have this issue, and do you recommend new tips?