RTL languages are NOT supported correctly in Skype for years, and it's about time to fix it!
For many years, Skype does not implement the BIDI algorithm correctly on their controls.
On the classic version working with an LTR GUI doesn't allow you to read properly RTL sentences that include some LTR words, and the same is on an RTL GUI, which then LTR sentences with some RTL words also can't be read properly. It is true, both for chat sentences,
and for the entire GUI.
On the current version (8.30.0.50) changing the GUI language to an RTL one, still leaves the chat area in an LTR state, which prevent the user completely from being able to read properly any RTL sentences that contain some LTR words.
BTW, trying to mark a mixed text was a mayhem in the past, and now it is just a difficult task.
There was a hope that when Microsoft acquired Skype, these problems will be solved, since MS knows very good how to implement BIDI correctly on their products. Unfortunately that didn't happen, I guess since the Skype team is the same team, and no one on Microsoft
ordered them to do so. All they need to do is to sit down with BIDI experts from MS themselves, or at least use native MS controls which support BIDI correctly.
You got many requests in the past years to solve this issue, and it's about Skype will finally be an RTL friendly, like any other regular application.