I don't have an answer, but I verified this with the following
bpftrace script and using the action of switching to zsh/oh-my-zsh
from bash.

---
tracepoint:syscalls:sys_enter_open,
tracepoint:syscalls:sys_enter_openat
{
printf("sys_enter_openat mode:%ld filename:%s (%ld)\n",
args->mode, str(args->filename), args->filename);
}
---

Here's some example data (not all the generated output) with spaces
around some of the issue lines:

sys_enter_openat mode:0 filename: (94797689127022)

sys_enter_openat mode:0 filename:/usr/lib/locale/locale-archive
(139635662831568)
sys_enter_openat mode:0 filename:/usr/share/locale/locale.alias
(140728940893664)
sys_enter_openat mode:0
filename:/usr/share/locale/en_US/LC_MESSAGES/git.mo (94797710736928)
sys_enter_openat mode:0
filename:/usr/share/locale/en/LC_MESSAGES/git.mo (94797710737472)
sys_enter_openat mode:0
filename:/usr/share/locale-langpack/en_US/LC_MESSAGES/git.mo
(94797710737712)
sys_enter_openat mode:0
filename:/usr/share/locale-langpack/en/LC_MESSAGES/git.mo
(94797710737584)
sys_enter_openat mode:438 filename:/dev/null (139809161489144)
sys_enter_openat mode:0 filename:/etc/ld.so.cache (140236659837824)
sys_enter_openat mode:0 filename:/lib/x86_64-linux-gnu/libpcre2-8.so.0
(140236659879440)
sys_enter_openat mode:0 filename:/lib/x86_64-linux-gnu/libz.so.1
(140236659639520)
sys_enter_openat mode:0 filename:/lib/x86_64-linux-gnu/libpthread.so.0
(140236659640784)
sys_enter_openat mode:0 filename:/lib/x86_64-linux-gnu/libc.so.6
(140236659642080)

sys_enter_openat mode:0 filename: (94426721874030)

sys_enter_openat mode:0 filename:/usr/lib/locale/locale-archive
(140236658581456)
sys_enter_openat mode:0 filename:/usr/share/locale/locale.alias
(140728357496384)

I'm tempted to think that this is some behavior of the system I don't
understand yet, rather than being a bug. But I can't say for sure.

Tristan