Hello,
1) We made code improvements of our price filter for this site https://kwiaciarnia.dobracena.store/
Do the backup of the XStore theme and XStore core plugin before the WordPress downgrade. Upload theme and core plugin from backup after the WP downgrade.
2) We don’t have WP Dashboard access to this site
https://kwiaciarnia1.dobracena.store/
So, provide us with WP Dashboard and FTP access to that site to check the mentioned issues.
Regards