Having upgraded software in march I took my R5 mkii to the arctic, at temperatures of minus 18 to minus 28 it just shut down ( lasted about 5 images) changing battery for warm ones made no difference, someone else there had similar but less severe, nikon on Sony users were find. I have contacted canon (uk) having had unhelpful responses from first person I asked for a senior person- again he was uninterested and just went back to it’s only designed for use above zero. I have seen on other forums that this is not an isolated issue, but also seems to happen to some and not others.