When I bought my R5 last year, Canon had a promo of AU$300 back or a CF card with a card reader thrown in. Naturally I opted for the CF card. As it turns out the card is Sandisk 512gb Extreme Pro and the reader is a Sandisk CF reader. Wow, would cost me AU$800 + here in Australia.
Anyhow, I digress. The card formats in the R5 and gives me the usual dirs of DCIM and MISC and no issue taking photos. Formatting in the reader (I always use the reader to transfer my files to HD) does not give me the two directories when I format but when put back into the R5 the dirs are reinstated when I take the first photo. Normally I would reformat in camera but tried it in the reader for the sake of this thread and have no issues.