ð & ß - wght: 100/400/900 | wdth: 100 | slnt: 0 | GRAD: 0 | opsz: 14

* - ð - Inconsistent treatment of the stroke placement vs the ascender ( how much is one each side ) and the relative weight of the stroke compared to the ascender which gets a bit to extreme in the black weight.
* - ß - This doesn't feel like a familiar construction of the upper case Eszett. Workhorse designs like Roboto should probably not be as eccentric as this even for a relatively infrequently used character.

I am guessing similar issues may exist in other parts of the design space but these glyphs are less central than many so I'll circle back to check the rest of the design space later. Also, this may be enough to say.