Ligature rendering sometimes renders with extra spacing

[LukeXuan]

I confirm that...

• I have searched the issue tracker, documentation, FAQ, Discourse, and Google, in case this issue has already been reported/resolved.

• I have read "How to Debug Issues", and will use it to provide as much information about this issue as possible.

• The issue can be reproduced on the latest available commit of Doom.

• The issue can be reproduced on a stable release of Emacs, such as 27, 28, or 29. (Unstable versions end in .50, .60, or .9x)

Expected behavior

Ligature should look normal

Current behavior

When I open emacs, sometimes this is what I see

Notice the extra spacing at the end of each ligature. This behavior happens regardless whether I configure ligature.el directly or through doom module.

Steps to reproduce

1. open Emacs
2. stare at the extra spacing

System Information

https://gist.github.com/LukeXuan/7e1f0edaca4fa8ac3328d6f16f69b276

[LukeXuan]

I reported in upstream earlier. Since then I tested a few days with only ligature.el and no doom emacs, and the problem didn't occur once. Unless I'm extremely unlucky, this seems like a emacs only issue.

Also, my font configure:

(setq doom-theme 'doom-one
      doom-font (font-spec :family "JetBrains Mono" :size 16 :weight 'medium)
      doom-symbol-font (font-spec :family "JetBrains Mono" :weight 'medium)
      doom-variable-pitch-font (font-spec :family "JetBrains Mono" :weight 'medium)
      doom-emoji-font (font-spec :family "JetBrainsMono NF" :weight 'medium))