Some time ago (maybe 3 months) I've noticed some problems with the bidi support (right-to-left languages) in org-mode.
One problem I can't reproduce: The characters have then a strange form but If I change the text scale (larger or smaller) it becomes normal.
The second problem I can reproduce, you can see it in the two images:
In this image: I have the option
bidi-paragraph-direction: nil (the same if I put in the first line:
-*- mode: outline -*-), to get the right direction for Hebrew and Arabic. As you see the headline color isn't consistently brown. The English text don't have this problem.
In both examples my init file is empty. And I've tried many fonts. My org version is 9.3 and emacs version is 27.1.
Actually, the first problem is bigger for me but I can't reproduce it; I think that both problems appeared a the same time. So maybe solving the second will solve the first one too(?)
EDIT: I can reproduce the problem with the colors also on a Windows machine with latest version: emacs 27.1 and the included org 9.3. With the older version: emacs 26.3 and the included org-version 9.1.7 I don't have the problem - at least I didn't see it.
EDIT 2: The same problem happens in outline-mode. So maybe it's not an org-mode problem. (Thanks to Samim Pezeshki)