FTE QC PERSISTENTTEMPSTRINGS

From Quake Wiki

This is the ultimate upgrade for multiple tempstrings.

The engine implements some form of GC, allowing tempstrings to last for however long as needed, and without string categories messing up saved games. This means that there is no need to use strzone/strunzone and in fact those builtins exist purely for compatibility - strzone simply returns a new tempstring and strunzone does absolutely nothing.