AST in given environment is actually signal handler. It can happen at any moment, therefore possible activities in AST are very limited. One of the rules is that there should be no new/delete operators during AST processing. But database snapshot AST is using class ClumpletWriter, which may perform memory allocation when clumplets are added to it. corrupting therefore dbb_permanent memory pool.
I do not have direct confirmations that it happens, but do have 2 core files, where dbb_permanent is corrupted, and it's known that people who got that cre files were actively working with monitoring tables.