Intonation Problem in rev. OS: Windows 10 (10.0), Arch.: x86_64, MuseScore version (64-bit): 3.5.0.13199, revision: github-musescore-musescore-43c5553
The basic clarinet sound is significantly sharp on at least some notes such as B in the middle of the staff.
I found that Clarinet 1 is not as sharp, and clarinet 2 and clar expressive are on-pitch, however one has to be aware of the other available sound-fonts, and go wading through the un-organized list of them to find the alternatives.
Comments
You need to mention which sound font this is in because not too many people are going to wade through the un-organized list of sound fonts to figure out which sound font you are using. ;-)