It sounds like there is a fret issue. If it is a new instrument, talk to the place where it was purchased… that’s the easyiest answer, but beyond that it shouldn’t be an issue that is too difficult to address. Examine the ninth and adjacent frets to ensure they are not damaged. Also tap the 10th fret to ensure it is not loose and springing into the way (a tapped fret will often sound different if not set correctly). If nothing is found there, try to get a straight edge that will span three frets in that region (it would need to be pretty small to cover 3 frets in that range). Set the straightedge over the 7th, 8th and 9th. Check to see if it can rock back and forth (if the frets are level, it should not). Then check 8, 9 and 10. Then 10, 11 and twelve. If the 9th fret is low and the others are even, it could be driven in further than it’s neighbors. A luthier might opt to re-set that fret. If the 10th fret is set fine but is too high, a fret level will take care of that. In fact, a fret level, crown and polish will take care of the problem regardless (unless there is a problem such as a loose fret). Plus, a fret level will allow you to get the best playing out of just about any instrument. However, if the 9th is just way low, you may not want to take the rest of the frets down to compensate.
I kind of just fired it all at you rapid fire. If my explanations need clarification, just let me know.