Was the GPU VRM temperature shown as "GPU VR VDDC Temperature" or "GPU VR MVDD Temperature" under the main GPU sensor, or as a separate value under a dedicated VRM sensor ?
If the first was your case, then it depends on the drivers used.
If the second, you will need to enable the new "GPU I2C Support Force" option in main settings / SMBus/I2C, because access to the GPU VRM can cause several issues and was disabled by default in new version.