I have a serious dropoff from people who click on my ads and people who actually land on the website (sometimes even 30%-40%). Where is the problem?

The page speed load time is most probably the problem. Check the page speed load time. You can try this app to help you out with the speed: https://apps.shopify.com/plug-in-speed

SEE THE CHEATSHEET ON SPEEDING UP THE WEBSITE: http://www.alexfedotoff.com/wp-content/uploads/2019/10/Cheatsheet-For-Speeding-Up-The-Website.pdf

What can cause Facebook to restrict a personal profile from advertising and how do you go around this?

Facebook can do this if you have multiple banned accounts or if you consistently break the policies. Also if you login from multiple locations into your account. ALWAYS use BM to login into accounts especially from unusual locations. You need to appeal and use this template: I used a VPN for other services. and maybe its the problem because I forgot to disconnect when using facebook.