Hi
It does not do anything special, meaning it uses the Zoo Joomla router.php file.
If you were using the Yoonique plugin for sh404SEF, the only way to keep these URLs is for the Yoonique developer to update their plugin to the 4SEF new plugin format which is fully documented here.
As a starting point, you can import existing sh404SEF Zoo URLs into 4SEF and they should work but new URLs will not follow the same pattern most likely - although I don't know which part of the URLs that Yoonique plugin helped you removed and whether there was any improvement or changes in Zoo for Joomla 4 in that field.
Best regards
Yannick Gaultier
weeblr.com / @weeblr