Miklós Galicz posted a short article on how he managed to override Laravel's str_slug helper function.

Long story short, until this is resolved one way or another... A really obscure but powerful tool can be a temporary solution for this. It's called Helper Overloading. Laravel's helpers are created in a way that checks if the method already exists. ... This is really great, the only thing remaining is to actually add our own method before Laravel creates it own version.

https://blackfyre.ninja/blog/fixing-slug-generation-problems