How to use gitk on Mac OS X 10.15.4

There is no gitk in git 2.26.0 which is installed in Mac OS X 10.15.4

I have to move git back to 2.23 with steps below

brew unlink git

cd homebrew-core
cd Formula
git checkout d04b60b58 git.rb
brew install git.rb

git --version

gitk

High resolution support.

$ brew cask install retinizer

open /System/Library/Frameworks/Tk.framework/Versions/Current/Resources/

Drag Wish and drop into Retinizer