The arabic font used fir words and sentences is way too small for me. Especially orange text is impossible to read, unless I activate magnification. I have set a larger font in my preferences, and English text us very readable.
Please fix, because this is going to be a showstopper (for me). Thanks
In the meantime, here is a chrome extension that will change the font to something you may find more legible: https://mimalef70.github.io/fontara/
Add it to chrome then when on the website hit the checkbox next to the duolingo favicon and the page will reload with Arabic & Persian Fonts changed to the new (imo) more legible font