I use the latest LTS release of Ubuntu, which is Ubuntu 22.04, and the library versions are what Ubuntu provides. So these are the libraries that most of us use when using Ubuntu LTS. Regardless, I am happy that tcmalloc and jemalloc continue to improve.
Occasionally I get "your version of X is too old" when I publish results for X, and I have had mixed results in the past when doing even more work to test the newer thing. In this case I am not going to put in that extra time. But in a few years I might revisit the topic and get newer versions of X, of course, there will be feedback that the version of X I test in 2028 is from 2026 and the story repeats.
But the thing that doesn't get much discussion in public is the drama that happens from upgrades when behavior changes WRT file systems, kernels, device drivers, CPU frequency governors, etc.
It took a few weeks to figure that out for several of my servers. So I am slow to upgrade things once that gets stable -- and it has been stable for my servers for about 6 months.
Nowadays, there are at least two different versions of tcmalloc: the one from https://github.com/google/tcmalloc/ is newer (it has rseq support, for example), and the version bundled in https://github.com/gperftools/gperftools.