This might be my host (SiteGround) trying to implement its captcha. It's definitely tied to my current home IP addresses as if I visit from my cell phone on cellular data (different IPs) I can access the site. This is good at one level as it is likely not affecting anyone else.
If I clear my browser data and reload I see the cookie info acceptance banner at the bottom of the screen, this too loads over and over. So I don't know what's coming from Siteground and what is coming from Ezoic/Cloudflare. I can't access any logs to find out.
It is strange though that it only seems to affect the front page. I can access other pages on the site with no issue.
Update: I've reset my router and obtained completely different IP addresses for my home network and I am still experiencing this and only on the front page. All other pages are accessible and navigable. It's just the index page affected.
Edit: It also doesn't seem likely to be Siteground knowingly doing this because I can log in to my control panels etc. and they would therefore have my IP addresses, so would be unlikely to block them.
Update 2:I used Leap to clear the cache for the front page and now I can load it. So something 'rogue' had gone into the cache it seems.