Front not loading properly, or not loading at all

Dear Newspaper support team,
We are having an issue on the following website:
https://zeleneprice.info

The front-end is not loading properly in certain moments, both on Google chrome and Safari, and mobile devices. We couldn’t distinguish what causes this error, as these issues appear to happen randomly from time to time.
We have seen a few scenarios:
– Page not responding at all
– Blank page
– Page loading very slow
– Page displayed in broken layout

Please let us know what could be causing this problem and how we can solve it.

Best regards,
Dragan Gucunski

Dear support team,
we have gone thru all the recommended steps and are still facing the same issues.
When we deactivated all the plugins, the problem is still there.
Likewise, when we deactivated the Child theme, the problem is still present.

Only once we changed the theme from Newspaper to Twenty Twenty-One , all issues disappeared.

With Newspaper theme, the page is still loading very slow, it seems to load all the content but in the background is still processing, trying to connect, so the menu doesn’t load for several minutes or not at all.

Also, when we go to the theme panel in backend, we see the following error:

Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 4193088 bytes) in /home/zelene/public_html/zeleneprice.info/wp-includes/wp-db.php on line 2056
Postoji kritična greška na vašem veb mestu. Molimo vas da proverite sanduče svoje upravljačke e-pošte za uputstva.
Saznajte više o otklanjanju grešaka Vordpresu.
Warning: error_log() has been disabled for security reasons in /home/zelene/public_html/zeleneprice.info/wp-includes/wp-db.php on line 1489
Warning: error_log() has been disabled for security reasons in /home/zelene/public_html/zeleneprice.info/wp-includes/wp-db.php on line 1489

We are sending you the System Status Tab screenshot below.

We hope you can help us solve this issue.