I have tried various tests by changing the PHP version on different servers, but nothing changes.
for exaple this:
Deprecated: json_decode(): Passing null to parameter #1 ($json) of type string is deprecated in /home/customer/www/colourmecoach.com.au/public_html/plugins/system/helix3/core/classes/menu.php on line 456

I am seeking your assistance, please.

Dear sir
For announcements related to the helix3 plugin, you can submit support here
www.joomshaper.com/joomla-templates/helix3
Thanks!