Difference between old and new R5 for wildlife and using an adapter

[Far-Out-Dude]

My questions are these, how much more and why would the R5 Mark ii work better for wildlife photography than the original version?

Second question, I can manage to get the R5 Mark ii but would not be able to afford an RF lens for now,  I am looking to get the Canon 2972C002 lens adapter so I can use the EF lenses I have (Mainly the Canon EF 100-400mm f/4.5-5.6L IS II USM Lens will be used for wildlife and moons shots) Are there any problems I need to know of when using this adapter? I already use one to use my EF lenses on my Canon M50 that is an EF-M mount but everything is different so I thought I should ask.

Looking forward to the difference in image quality,

[Tronhard]

Well... although the R5II has been announced, as far as I understand it, the firmware is not fully confirmed yet - apparently it's v0.05 which is not a full release, and there is a very limited constituency of people who have access to the hardware.
Consequently, I would hold your enthusiasm and questions until full production versions are available.
Given that the EF100-400 L MkII lenses have worked flawlessly with the R5, I see no reason why they would not work equally with the new version.   It would not be in Canon's interests, or that of their market to let that compatibility lapse.