Why does my R6II keep cutting out?

General event photography - Not shooting video or H+ speed bursts (just H and “slow”) Normal weather conditions (10-20c). Switching between RF and EF L lenses with the Canon adaptor. Power saving options switched on. Primarily CRAW. Latest firmware loaded.

Body just wigs out and shuts down - only rebootable by pulling the battery out.

Never in nearly a million shots across to 5DIVs did I have this problem once - but it has happened 4-5 times in the last few weeks.