One of our customers sent us a message similar to the following.
It shouldn't be an issue on your end, nor of your website, because Google stops showing ads after a few impressions to the same person.
Time to First Byte (TTFB) is the total time spent to receive the first byte of the response once it has been requested.
The scores PageSpeed and YSlow presented in the GTmetrix report represent the web development quality of your page.
Your browser shows a warning symbol and displays a message saying your connection to this site is not fully secure.
Cross-origin resource sharing (CORS) is a mechanism that allows restricted resources on a web page to be requested from another domain outside the domain from which the first resource was served.
Assuming there are no issues on your web server configuration and the remote server is online, you may want to check if the SSL Certificate associated with the external entity is valid.
Check the error log file for errors. Coding errors on your website are most likely causing the blank pages.