Website getting critical error message

So I’ve had this website set up for close to two years. I had a bad hack but my web hosting scrubbed it clean. Then it was back and I went to my redesign I went through.

i am using the theme Sinatra and using elementor for design. I have a plugin called royal add-ons which connects with elementor. I have woo commerce and some of their extensions for Mailerlite, tax, and shipping.

but people keep getting a critical error page. But only sometimes. Because I just had someone use my form 48 hours ago and another tell me they got the message less than 24 hours.

im so confused. I thought it might be my event plugin or learn press but I’m just stumped. What else should I try??

The page I need help with: [log in to see the link]