Completion issue with ack formula

[cscetbon]

brew gist-logs <formula> link OR brew config AND brew doctor output

$ brew config
HOMEBREW_VERSION: 4.4.13-31-ge330f37
ORIGIN: https://github.com/Homebrew/brew
HEAD: e330f371f880a020310ba9428d6e8a4d5c1021f4
Last commit: 16 hours ago
Branch: master
Core tap HEAD: b3dfaeb1f4b2930f3e5b36871122e9c29d063e5e
Core tap last commit: 3 months ago
Core tap JSON: 26 Dec 17:05 UTC
Core cask tap HEAD: 1ad9c2bb35c21a34c5e2dbb791cdf5f4d2e38cce
Core cask tap last commit: 3 months ago
Core cask tap JSON: 26 Dec 17:05 UTC
HOMEBREW_PREFIX: /opt/homebrew
HOMEBREW_CASK_OPTS: []
HOMEBREW_GITHUB_API_TOKEN: set
HOMEBREW_MAKE_JOBS: 8
HOMEBREW_SORBET_RUNTIME: set
Homebrew Ruby: 3.3.6 => /opt/homebrew/Library/Homebrew/vendor/portable-ruby/3.3.6/bin/ruby
CPU: octa-core 64-bit arm_blizzard_avalanche
Clang: 16.0.0 build 1600
Git: 2.47.1 => /opt/homebrew/bin/git
Curl: 8.7.1 => /usr/bin/curl
macOS: 15.2-arm64
CLT: 16.2.0.0.1.1733547573
Xcode: N/A
Rosetta 2: false

$ brew doctor
Please note that these warnings are just used to help the Homebrew maintainers
with debugging if you file an issue. If everything you use Homebrew for is
working fine: please don't worry or file an issue; just ignore this. Thanks!

Warning: You have the following deprecated, official taps tapped:
  Homebrew/homebrew-cask-fonts
Untap them with `brew untap`.

Verification

• My brew doctor output says Your system is ready to brew. and am still able to reproduce my issue.
• I ran brew update and am still able to reproduce my issue.
• I have resolved all warnings from brew doctor and that did not fix my problem.
• I searched for recent similar issues at https://github.com/Homebrew/homebrew-core/issues?q=is%3Aissue and found no duplicates.

What were you trying to do (and why)?

type ack -- then tab

What happened (include all command output)?

Getting those errors

_arguments:comparguments:327: invalid option definition: --[pytest       Filename matches (?^i:_test[.]py$); Filename matches (?^i:^test_.*[.]py$)]
_arguments:comparguments:327: invalid option definition: --[pytest       Filename matches (?^i:_test[.]py$); Filename matches (?^i:^test_.*[.]py$)]
_arguments:comparguments:327: invalid option definition: --[pytest       Filename matches (?^i:_test[.]py$); Filename matches (?^i:^test_.*[.]py$)]

What did you expect to happen?

I should get the list of the available options

Step-by-step reproduction instructions (by running brew commands)

brew install ack
ack --<TAB>