Here is the steps that solved my problem for T15 Lenovo on manjaro KDE
Install 5.8 Kernel mhwd-kernel -i linux58
Reboot computer reboot
Check your kernel version it should be 5.8 at least mhwd-kernel -li
Currently running: 5.8.3-2-MANJARO (linux58)
The following kernels are installed in your system:
linux57
linux58
Install pulseaudio-git https://aur.archlinux.org/packages/pulseaudio-git git clone https://aur.archlinux.org/packages/pulseaudio-git cd pulseaudio-git/ makepkg -si
Install missing firmware and conf sudo pacman -S sof-firmware alsa-ucm-conf
Reboot (yes again and i don’t know if it’s necessary but do it anyway) reboot
Start pulseaudio then kill it then start it again (weird but thats what fixed the problem for me after following the previous steps) pulseaudio --start pulseaudio -k pulseaudio --start
And voila !
Full credits goes to pobrn and bogdancovaciu for the solution