Bug report: gitk is no longer working on my OSX machine

Hello,
Would love some help, having trouble getting gitk up and running again...

Here's the details from `git bugreport`:

What did you do before the bug happened? (Steps to reproduce your issue)

1. Open any git repository directory in a terminal.
2. Run `gitk`

What did you expect to happen? (Expected behavior)

gitk opens

What happened instead? (Actual behavior)

gitk crashes with the following error message on the command line:

objc[33662]: autorelease pool page 0x7fb1070a3000 corrupted
  magic     0x00000000 0x00000000 0x00000000 0x00000000
  should be 0xa1a1a1a1 0x4f545541 0x454c4552 0x21455341
  pthread   0x10b020dc0
  should be 0x10b020dc0

An error window also pops up saying that "wish quit unexpectedly."

What's different between what you expected and what actually happened?

It shouldn't crash.

Anything else you want to add:

I'm using git/git-gui as installed by brew on OSX>

If I run `gitk` where outside of a git repository, then it opens fine
(and shows the "Cannot find a git repository here" error.

gitk has run fine on this computer for years; I don't know what
suddenly changed to make it stop working.

[System Info]
git version 2.30.0
cpu: x86_64
no commit associated with this build
sizeof-long: 8
sizeof-size_t: 8
shell-path: /bin/sh
uname: Darwin 19.6.0 Darwin Kernel Version 19.6.0: Tue Nov 10 00:10:30
PST 2020; root:xnu-6153.141.10~1/RELEASE_X86_64 x86_64
compiler info: clang: 12.0.0 (clang-1200.0.32.28)
libc info: no libc information available
$SHELL (typically, interactive shell): /bin/zsh


[Enabled Hooks]