API-Level in Score Properties dialog shows the one from the version running, rather than the one from the score
So it shows 206 in MuseCore 2.0 and 2.1, 300 in MuseScore 3.0, regardless which version the score had been written (or last saved) with.
Opening a 2.0 score should show 206 or 2.06
Opening a 1.x score should show 114 or 1.14
Only opening a 3.0 score should show 300 or 3.00