I just took this grey squirrel photo on the off-chance, and was rather pleased that it came out pretty well. ISO25600 is far from ideal, and it has been got at by Topaz AI (which, when it works, definitely works!).
Canon R6 + RF 600mm lens
Kept dark as it seemed to suit.
Let’s see if this works
This is the JPG from Canon’s DPP4, so still noise removal but nothing like as directed. The improvement is not that obvious until you zoom in, but moves the photo from ho-hum to just about shareable.