No, I haven't, but I know other users who have returned R5 cameras to Canon, and have been told that Canon can't reproduce the malfunction. I don't have a spare RF-mount body, so I don't want to be without a camera for 2-3 weeks while Canon tests it, especially as I anticipate that they'd devote insufficient time to testing it. Incidentally at least a couple of people here have reported that Canon have replaced the mainboard of their R5 in an attempt to fix the freezes, but that the problem persists afterwards.
I don't think an "auto-restart" feature would solve the problem, because switching the camera off and on again fails to fix it. The only way to get it operational again is to remove and reinsert the battery (this never fails).
Incidentally, these freezes don't seem to be confined to the R5. There have been reports of R3 freezes, and I have a friend whose Nikon Z9 suffers similarly.
Hardware and software is so complex in modern cameras, that unfortunately I think there'll always be a percentage of cameras that malfunction under certain conditions. This is very apparent from the number of references to "bug fixes", or "improved stability" in firmware updates, and the frequent appearance of phrases such as "under rare circumstances a phenomenon may occur in which the camera becomes non-operational"...
It could be hardware or software, or a conflict between hardware and software. In my case the camera is fine most of the time, but locks up in a specific bird photography scenario, i.e.
SERVO AF with animal-eye AF
Shutter half-pressed for several seconds while anticipating action.
Shooting a series of short hi-speed bursts in electronic, mechanical or EFCS shutter.
I only shoot RAW normally, and I use fast Delkin and SanDisk CF-Express cards, but I'll experiment with shooting JPEG (which should prove whether or not it is a buffer problem). When the camera locks up, the red "writing to card" light remains illuminated for at least a couple of minutes, after which I get fed up waiting and reboot the camera.