It is being reported to myself and others that Canon is going to be releasing feature updates to both the Canon EOS R5 and Canon EOS R6 via firmware.
Rumored Canon EOS R5 Firmware Update:
Adding a low bitrate mode for RAW & IPB in all recording modes
Canon Log 3
I do find the mention of FullHD at 120p confusing, as the Canon USA site shows FullHD 120p as a feature already.
The Canon USA Pro Twitter account says it’s supported.
Full HD 120fps is supported. The EOS R5 specification information...