font problem - Bahnschrift

I've never seen glitches like that with the Bahnscrift typeface before. The glyphs don't type out like that in my copy of Adobe Illustrator. I've used the typeface in other applications (such as CorelDRAW) and never noticed any buggy corners like that. The glitches make me wonder if the font file in your computer could be corrupted. Since Bahnscrift is bundled into Windows 10 you might try copying the font from another computer system and then installing that on your machine.

By the way, do those odd pointy bumps continue to show if you change the OpenType Variable values in that typeface? What are the weight and width values of that type sample?

that font show in ai 2020 is no problem, just in ai 2019 have this proble...