Getting PHP error while upgrading to 8.0 or 8.1

I’m now downgraded to 7.4 while updating to 8.0 I’m getting this error.

Fatal error: Uncaught Error: Undefined constant “storefront_footer” in /home2/uozt1621/public_html/states-online-pharmacy.com/wp-content/themes/storefront-pro/functions.php:826 Stack trace: #0 /home2/uozt1621/public_html/states-online-pharmacy.com/wp-settings.php(585): include() #1 /home2/uozt1621/public_html/states-online-pharmacy.com/wp-config.php(93): require_once(‘/home2/uozt1621…’) #2 /home2/uozt1621/public_html/states-online-pharmacy.com/wp-load.php(50): require_once(‘/home2/uozt1621…’) #3 /home2/uozt1621/public_html/states-online-pharmacy.com/wp-admin/admin-post.php(19): require_once(‘/home2/uozt1621…’) #4 {main} thrown in /home2/uozt1621/public_html/states-online-pharmacy.com/wp-content/themes/storefront-pro/functions.php on line 826

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