Good find, yes that's a bug.  We'll patch it in the next release.

If you're comfortable editing PHP you can patch it as follows: 

• Open /cmsb/lib/menus/admin/general_server_info.php
• Search for:    fromArray
• Replace this: SmartString::fromArray
• With this:       SmartArray::new

Or alternatively, you can just temporarily uncheck this setting: 

Admin > Security > Developer Warnings [_] Disable PHP developer warnings: E_STRICT, E_DEPRECATED (only needed during development)

Thanks for the report!

I just upgraded from 3.71 to 3.74 on my beta install and noticed that I suddenly started getting deprecated warnings on the admincp. I am using PHP8.3

Deprecated: SmartString::fromArray() is deprecated, use "SmartArray::new($array)" instead.
/system/vendor/itools/smartstring/src/SmartString.php on line 703

This is a new addition since the previous version, so I was a bit surprised that it wouldn't be ready for PHP 8.3. The notice seems to get thrown into the log every time I try to load the 'General Settings' page and the details suggest the call comes from this URL:

https://www.MYDOMAIN.com/system/admin.php?menu=admin&action=generalServerInfoAjax&forceUpdate=1