I had Z15.3 for extended time before I installed Z16.3, so I think the first kernel I had with Z16.3 was 5.15.0-56.
I have read somewhere that Z16 initially had a 5.11.#-## kernel, but I can't confirm that from my own experience.
to test it, you must reboot, then enter the Grub Menu (tap esc or tab at boot) and from Grub menu, select Advanced Options for Zorin > Zorin on 5.15.0-83 to boot from.
That is odd... What troubleshooting did you try to fix Gnome Software Store?
The files on your hard drive are likely corrupted. I recommend booting to LiveUSB and running boot repair, checking your drive with a S.M.A.R.T. test and possibly running fsck from LiveUSB (Never ever run fsck on a mounted file system).