Character Encoding in Outlook app

Hi!

We have on premise Exchange Server 2019 and have character encoding problem in the Outlook app.

In the OWA and Outlook desktop verson there is no problem, only in the Outlook app.

for example:

Koll�g�k

We have already got this type of letter inside and outside our organization.

We use the latest version of the app, installed it directly form the play store.(we use only mobile phones with android) 

Is there a missing settings in our server exchange server?

Or is it an android outlook bug and we can not solve this problem?

Tthank you in advance for your reply!