Once, while traveling in an area without access to good stores or camera supplies, I needed a battery for my 5Diii. I was very fortunate to come across a knockoff at a market in one of the cities. It worked but the battery became quite warm with charging and did not provide many shots after signaling a full charge. Once I was back in civilization, I got some new OEM batteries and the temporary replacement was sent to the recycling bin.
I know that there are many brands of batteries in the correct sizes out there and we've seen recommendations of many used with great success in these forums. But, after spending thousands on my R5, I don't want to risk the camera being harmed. So for me, I am using the Canon LPE6NH that came with the camera, and 4 old Canon LPE6N's from my now sold 5Div.
BTW, even though there is an option to do so, I do not charge batteries in the camera. My paranoia says heat is not a good thing for our devices and I don't want to heat up the battery while charging in the camera.