Pi4: /sys/class/hwmon/hwmon?/temp1_input missing since Kernel 5.3.18-150300.59.71-default

I used to read /sys/class/hwmon/hwmon?/temp1_input to get the temperature of the Raspberry Pi 4.
This file does not exist any more in Kernel 5.3.18-150300.59.71-default and newer.
It was available latest in Kernel 5.3.18-150300.59.68-default.
The list of loaded modules are identical.

How can I get back this file or is there an alternative to get the temperature?
sensors(1) does not show any useful information.

(@admin: If the Hardware Sub-forum is the wrong place, please move it to the better one)