php upgrade on server caused highend 4.0.3 to crash

found that the issue is related to the theme ‘highend’ . If you wish your website to work on same theme, you need to contact theme vendor about the issue
php was upgraded to 7.4 on the server where my highend theme 4.0.3 website is and my site
went down with critical error message. Multiple people have tried to get the site back up and now I’m being told to contact the original maker of the highend theme. I’ve been using this
theme since 2015 and have rebought and updated it continuously. First time I’ve had this happen. Please advise thank you, Lisa