Canon has released firmware v188.8.131.52 for the Canon EOS R5C.
Please note that this firmware update must be performed in VIDEO mode.
Firmware Version 184.108.40.206 incorporates the following fix and enhancements:
Built-in Mic Audio Off
The internal microphone on the camera body can now be turned off. (VIDEO mode)
Fixes an issue, in which, in rare instances, the camera cannot be normally operated when operating the REC button with the camera set to the [Continuous Recording] function.(VIDEO mode)
Fixes minor issues when using the CINE-SERVO lens. (VIDEO mode)
Canon Support for EOS R5 C | Canon U.S.A., Inc.