It's because the points on that specific dot are defined the opposite direction clock-wise compared to the rest of the curves on that font. So the renderer interprets them as an inner contour and not an outer one.
As far as I could tell, orientation is defined as either TrueType (outer contours are clockwise) or as Postscript (outer contours are counter-clockwise). If I find a Postscript-style orientation I just flip them so the renderer sees a consistent input. But for some reason that dot either is avoiding the flip through FreeType or is defined the other way in the source font file itself.
A lot of renderers are agnostic to the orientation of the curves, but that can lead to its own issues and undesired filled/unfilled areas. So it's pick your poison here. IIRC Sebastian Lague also has to deal with it in his amazing video about rendering text.
I might go check the source font file and see what's up. This is Libre Baskerville which is Open-Source so maybe we can even fix it if it's an inconsistency at that level.
What happened to the dot of the italic "j" in the first video?