Like many, I've resisted buying spare OEM-branded camera batteries due to their cost compared to 3rd party batteries. I've used 3rd party batteries interchanging them with OEM batteries for years.

During a recent trip to the Tetons my Canon R5 was shooting fine during the day, however when I went to download images in the evening the camera wouldn't turn on. Popped the battery out and charged it about 20-minutes then put it back in. Camera turned on and displayed a message asking if this was a Canon branded battery. Either a Y or N response (with either Canon or non-Canon batteries) resulted in a display of "Battery may be counterfeit, shutting down to protect you". After returning home and preparing to call Canon support, the camera came on and appeared to be working, but then I quickly noticed many of the buttons were not working.

Shipped it to Canon repair (ouch the cost of insuring it with UPS!) and a $496 repair bill later the camera is now working fine again. All 3rd party batteries have been disposed of, and a new $79 Canon battery on order (out of stock and back ordered of course). Fortunately, I now have the R5 and R7 bodies that use the same batteries.

Lesson learned the hard way.