Tips on how to check if black/purple peppers are ripe? Last one I picked was all dark outside, but still green and bitter inside

Pic 2 is how they should look when totally ripe – the one I picked was still pale green inside, despite looking dark outside

Pic 1 is my peppers. The one with the green ? could be ready, but that’s about how my last one looked.

Is there a tip you use to determine ripeness without cutting one open? It seems so much easier to tell with more standard red-yellow peppers

These are sweet pepper “Black Knight F1” – I know this is predominantly a spicy pepper sub, but I figured the philosophy is the same!