Firmware 1.1.0, released on 27 August 2020, was the first update to address the EOS R5's thermal behaviour.
Canon's notice states that temperature detection and shooting time control in video shooting have been improved, and that the total shooting time when short-time recording and power-on/off are performed repeatedly at room temperature is improved. Useful messaging is now displayed when HDMI display is set to camera plus external monitor while overheat control is on.
The update also corrected a case where the available movie recording time was displayed incorrectly when date, time and zone were not set, improved in-lens stabilisation during movie shooting with certain RF lenses, improved FTP connectivity, and fixed longer card access times with certain CFexpress cards.
None of this removes the camera's recording limits. The update is recorded here because it changes the behaviour owners experience, which means an ownership report about overheating is only interpretable alongside the firmware version the camera was running.