to maintain Windows:

1. disable BitLocker (Impostazioni->Aggiornamenti Sicurezza->Crittografia->Disabilità)
2. disable Secure Boot (from BIOS)
3. re-order the booting devices (from BIOS)
3. use a USB to boot the ubuntu 21.04

Backlight / nomodeset

In case you are using a laptop with intel i7 gen. 11th and iRIS XE graphics you should use kernel 5.11.0-16-generic

Wi-fi
To install the correct drive you should follow these command (and might read the discussion at this link):

1. Make sure you have a proper build environment and dkms installed.
2. sudo apt install bc module-assistant build-essential dkms
3. sudo m-a prepare
4. apt install rtl8821ce-dkms