Short trills are wrongly imported as mordents (the vertical line should not be there).
There is already a thread on this from some time ago. The situation is known and has been much discussed.
Minefield ahead… https://www.steinberg.net/forums/viewtopic.php?f=246&t=108994
Better to divert the OP to the original thread than have this whole argument repeated.
Thank you, Derrek. I did search and saw a post mentioning mordents but it looked more like a debate over what a mordent is rather than a bug report, so I thought I’d post a simple bug report.
I just checked 3 different editions of Bach’s Wohltemperierte Klavier, and found that Bach-Gessellschaft, Schirmer, and Henle all call the squiggly without the line “trillo” and the one with the line “mordent”.
The bug is that the MusicXML file opens with incorrect symbols in Dorico.
MuseScore imports the file with the correct symbols. I noticed that in the other thread a Dutch harpsichordist mentioned that he was the one who got the folks at MuseScore to get the ornaments right. So this is a MusicXML issue… and, probably yes, better to defer to the previous post.