Highend gives Critical error in PHP 8.0

Help! My domain hosting will not support PHP 7.4 anymore from November 28 and will upgrade to PHP 8.0. Then PHP 7.4 will not be longer available.

My site runs on the Highend theme (2.4.6) and gives a fatal error in PHP 8.0. Then I also can not login anymore to change my settings in WordPress.

The error should be in the theme:
Een fout van het type E_ERROR werd veroorzaakt op regelnummer 30 van het bestand /customers/5/a/7/paulontwerpt.nl/httpd.www/wp-content/themes/HighendWP/options-framework/classes/metabox.php. Foutmelding: Uncaught Error: Cannot call constructor in /customers/5/a/7/paulontwerpt.nl/httpd.www/wp-content/themes/HighendWP/options-framework/classes/metabox.php:30

Can someone please tell me what to do or how to fix this. I have updated my wordpress to 6.1 and deactivated my plugins, but still I get a white screen with ‘A critical error has occured on your site’.

When I click ‘more information’ I get the error message mentioned above.

I hope someone can help me.