Hi,
in the same PC is running php 7.3.33 and mysql 5.7.33
in my old env xoops 2.5.10
url /modules/system/admin.php?fct=users
when I access the page you will see the list of the user registered
if I press SEARCH button I can still see the list of the users
if I type 'ceca' (for example) and press SEARCH I see in list just one user (as it should be)

in the 2 new site in 2.5.11
where one is upgraded and one is fresh installed
same page url /modules/system/admin.php?fct=users
the behavior is the same for both new site
when I access the page you will see the list of the user registered
when I press SEARCH button the list is empy
If I search for a username I always receive not found and what I typed in the field disappear

Let me know if you need more info to troubleshoot
Carlo

Thanks for letting us know.

I was able to replicate it, and I'll be looking into it, hopefully soon. I'll keep you posted.

I have the same problem (www.audizioni.it) after upgrading to XOOPS 2.5.11:
Fatal error: Type of SmartyCompilerException::$line must be int (as in class Exception) in /web/htdocs/www.audizioni.it/home/site/class/libraries/vendor/smarty/smarty/libs/sysplugins/smartycompilerexception.php on line 8

This should be fixed with this commit:

Try to make the same changes in your installation and let us know if it worked.