Comment 32 for bug 1884981

I had similar issue.

Lenovo Ideapad 5 14ARE05 dual boot Windows 10 and Ubuntu 20.04 (Kernel 5.11 after update)

Solution steps:

(1) Update your Ubuntu 20.04 installation with all the latest update. This should update your Kernel too (mine updated to 5.11).

(2) Reboot

(3) Go to Windows 10 and Download and install Latest BIOS update and install it. In my case BIOS updated from V1.09 to 1.10.
***Be careful and pay close attention to the instructions shown by the BIOS update installer. Ideally you should fully charge your laptop before performing BIOS update and keep your charger connected.***

Running BIOS update will reboot your system and change BIOS settings to default. If you had disabled secure boot to install and dual boot Ubuntu then this will enable secure boot option. You will need to disable it again. Once BIOS update is completed reboot and go to BIOS (F2)

(4) Disable secure boot in BIOS again

(5) Boot to Ubuntu. (Tip: Use F12 key to boot to Ubuntu if you do not get Ubuntu Grub Bootloader Menu. You can change the boot order from BIOS settings (F2) permanently)

Your touchpad should start working.