Issue is reported at  There seems to be a memory leak in SAX2.c but apparently the patch is only in the master branch, not in the version used in rhel 9.x.

The issue appears to be resolved in the master branch, but the master branch has a rewrite of the code in tree.c

Patch reverting Make xmlFreeNodeList non-recursive appears to avoid the leak.

Approach should be to rewrite the above patch to still avoid the recursion but also avoid the leak.

Note that there were a few other reports of high memory usage that were pointing to possible libxml2 issues (waiting for valgrind logs from user).