What brand, model, and capacity memory card are you using?
I recommend full size UHS-i U3 cards with a max capacity of 32GB.
Try this! Leave the memory card out of the camera. Close the door, and turn the camera on. Turn the camera off. If the problem went away, then your microSD cards are the issue.
As my esteemed colleague Waddizzle commented, your use of Micro SD cards could be an issue, but even if not, they present a risk because of the fact they have to use an adapter to fit into your full-size SD card slot. It is far more reliable to use a full-size card.
The main thing is to get a card from a reliable source - there are lots of counterfeit cards on the market and they should be avoided. I personally use SanDisk and Lexar cards - capacity is what you can afford, but larger cards are usually faster. The thing to do is become familiar with card speeds, and it is the write speed that is most critical, not just the read speed, that most manufacturers tout because its the faster metric.
12/05/2023: New firmware updates are available.
09/26/2023: New firmware updates are available.
08/18/2023: Canon EOS R5 C training series is released.
07/31/2023: New firmware updates are available.
05/18/2023: New firmware updates are available.
03/30/2023: New firmware updates are available.