if there's a hint of overheating in R6ii, then avoid like the plague. Canon will have learned nothing.
but lets be more specific and even Sony cameras overheat although they have menu options to allow higher temperatures before shutdown.
I can't speak to the R6 but the R5's "overheating" hype was whipped up by the Sony fanboys as a reaction to Canon's technical superiority 2 years ago. It only affected 3 video modes: 8k, 4k120 and 4kHQ. All other video modes and stills shooting was not affected. Since release, firmware updates have removed the timer and using actual internal temperature measurements, improved algorithms, added "light" video modes and added the menu option to allow higher temperatures before shutdown. Sony still cannot record 8k30 raw for any length of time.
To remind the viewers of the evolution of what happened I have borrowed this...
Somewhere in a galaxy not far from here, within 6 months of announcements…
Internet: Canon could never put 8K full frame in to a mirrorless camera. They don't have the technical capabilities to do that. The last time they innovated was when 5d mkii was born.
Canon: Our next 5 series will have 8K and demonstrate what we are capable of.
Internet: (spits coffee on screen) Yeah right. Maybe 8K timelapse mode
Canon: No, 8K video
Internet: Er no, 8K like 15 second movie burst mode then, because you know overheating would happen in such a small body. Do Canon engineers not know anything about physics? That's why refrigerators exist....
Canon: No full 8K video
Internet: Yeah right.... hahaha. It's not possible. So no AF or IBIS then. You won't be able to use the full technologies of the camera/
Canon: No. 8K Full frame, AF and IBIS enabled.
Internet: It's not possible, because you know.... overheating is a thing with technology in such a small package. If it was possible then Sony would have done it.
Canon: Hold our beer.....
Post launch
Internet: I demand a full unconditional apology from Canon. I demand immediately that they give us unlimited 8K full frame video for $4.99 and stop hiding behind this "overheating" scenario to protect their other cameras. I’ve never felt so personally insulted by a camera company as I have by Canon. To me honest behaviour is very important. I recognize that the only person that is perfect is me and people make mistakes. The important thing is to admit that and not to sell us totally unusable technology like this…