Permalink for CPT without archive but including taxonomy returns 404 on all other pages and posts

I’m trying to achieve the following permalink structure for a Diensten custom post type:
https://domain.com/%taxonomy%/%postname%/

With the code below I’ve achieved the desired permalink structure however it returns a 404 on all other posts and pages…

It has something to do with the fo_diensten_permalink function as it seems to target all posts and pages and not just the diensten custom post type. According to this link https://shibashake.com/wordpress-theme/custom-post-type-permalinks-part-2#conflict it can be resolved by adding a unique slug into the permalink structure. However when I do that it breaks the custom post type permalink structure. On the other hand, it solves the issue with the 404 for the other pages and posts.

This is the code that I’m using to register the Diensten post type:

Registering the Type diensten taxonomy’

The rewrite function

Any help is much appreciated.