I still use my 70-200 2.8 II in my R5. Works perfectly. The adapter doesn’t concern me. I like the stubby RF version, it’s just not worth it for the smaller format. If a longer version II comes out I’d see less of a point to change. It might be a version III with a built in adapter. Canon will get me eventually. My 70-200 started getting wobbly. Then I learnt about all the screws under the rubber and once tightened it was perfect again. It’s a super lens.