Kernel v5.13 has been marked End Of Life in recent Manjaro update announcements
So you should install kernel v5.14 (or v5.15) using Manjaro Settings Manager GUI
( manjaro-settings-manager -m msm_kernel )
OR use this terminal command
sudo mhwd-kernel --install linux514
Archwiki suggests that onboard audio is working for kernels later than v5.14.2 with package sof-firmware installed to provide snd_soc_skl driver to support internal digital array microphones