Git auto completion does not work for comparing 2 files from 2 different branches

I compare 2 different files from git remote like this:

git diff origin/branch1:file.txt origin/branch2:file.txt

However, auto completion only works until this point: git diff origin/branch1:file.txt, pressing tab afterward does not bring me list of usable remotes, branches in the said remote, and files in the said branch, unlike first one in branch1, which auto completion works fine.

Steps to reproduce

Clone any repository with 2 or more branches
Try to get difference of 2 files using git diff origin/branch1:path/to/file origin/branch2:path/to/file
Observe that auto completion doesn't work for second one

OS is KDE Neon, 20.04

Terminal I used is Yakuake and Konsole

ZSH version is 5.8

I have attached video of me reproducing the issue.

From Hyun Bin, and thank you for your effort on this.