Hello,
We can see a few reasons for the mentioned problem, which are unique for your site, so other our customers do not face the problem. Here they are:
– errors from 3rd party plugins in the customizer https://prnt.sc/rMlYq-sJXvuY
– errors from 3rd party plugins on Home page which is loaded in preview mode – https://prnt.sc/fp2hgQtRnFg6
– size of Home page is 61mb https://prnt.sc/xttNxjWnbgxr
The most important reason is the page size of 62mb-68mb, which in the customizer turns up to 70mb. Accordingly, we download it at the same time 10 times and receive 700 MB of content that the server needs to process, but it does not cope.
possible solutions:
1) reduce the page size.
2) load the previewer on some neutral page, such as a blog, or just an empty page, although even empty pages weigh 50 MB on your site
Regards