WiFi driver issues in ASUS ROG G15 (2021)
I have the same laptop, and I am running Ubuntu 21.04 as well.
The solution for the wireless is upgrading the kernel to an stable version higher than 5.12+. I am running:
Asus-ROG:~$ uname -r
5.13.5-051305-generic
After I upgraded the kernel started working for me.
NOTE: wifi is working fine, with good speed tests, nothing to report, issue I still have is the Bluetooth connection.
Good luck