Why do these Nexus core files not show some function names in their stack traces?

During today's mupdate, we saw a couple of Nexus cores on gc08 which have been rsynced over to /staff/dock/rack2/mupdate-20240329/cores/sled-08. With both those cores, whether you do pstack or mdb with $c, you get something like:

libc.so.1`_lwp_kill+0xa()
libc.so.1`raise+0x22(6)
libc.so.1`abort+0x58()
0x5a207b9()
0x5a207a9()
rust_panic+0xd()
_ZN3std9panicking20rust_panic_with_hook17h7d19ef586749da2fE+0x2ab()
_ZN3std9panicking19begin_panic_handler28_$u7b$$u7b$closure$u7d$$u7d$17h95e3e1ca24551a68E+0xa4()
0x5a05ef9()
0x5a08802()
0x5a4f6c5()
0x5a4fd55()
_ZN95_$LT$nexus_db_queries..db..sec_store..CockroachDbSecStore$u20$as$u20$steno..store..SecStore$GT$12record_event28_$u7b$$u7b$closure$u7d$$u7d$17hc33ebb1cf636f348E+0xcec()
...

Why do the functions in the middle (0x5a05ef9 etc) not have their names in the stack traces? Maybe they're in std -- but if so, why does std::panicking::begin_panic_handler get shown?

I'm concerned that this issue may be more widespread somehow.

Start with the two cores under /staff/dock/rack2/mupdate-20240329/cores/sled-08 and reproduce the traces using pstack and mdb with $c. Compare the unnamed 0x5a05ef9-style frames with the named Rust frames. Done means explaining why those function names are missing and whether the issue is limited to these cores or more widespread.