I use JetBrains Mono font in Emacs and in today build from master, the Org documents display a different ugly (in my opinion) font. See the fields 

#+language: 
#+options: toc:2 H:3 num:2 email:t
#+include:

#+begin_quote
#+end_quote

in test.org-emacs29-01oct2021.png attached.

With the build I did a month ago *all* is rendered with the same font, just the color changes. See the attached test.org-emacs28-02sep2021.png.

If this is not a bug, How can I restore the previous behavior?

In my init file I have:

(set-frame-font "JetBrains Mono-11" nil t)

(setq default-frame-alist
      '(
        (width . 115) ; character
        (height . 49) ; lines
        ;;(fullscreen . fullheight)
        ;;(left . (- 0)); pixel
        ;;(top  . (+ 0)); pixel
        (left . 840); pixel
        (top  .   0); pixel
        (font . "JetBrains Mono-11") ; font
        ))


Ciao,
 Angelo.