For various reasons (mostly: people don't like debugging tools in production), it's now necessary to add
BuildRequires: glibc-utils
to RPM spec files if you use LD_PRELOAD=libc_malloc_debug.so.0 in package test suites during the build (we already discourage linking against libc_malloc_debug.so.0). This applies to Fedora 40 and rawhide.
Thanks, Florian