Well, this does not answer my question. I already new the option “maxlength”, as I mentioned in my question. Problem is, how can I make a slug longer than 128, not shorter.
It does not say that you can only shorten the slug.
By entering a value above 120, you can increase the slug length.
I have just tested it and it works perfectly.
Here is an example with 258 characters:
Okay, did absolutely not work for me, I tried several things. Must then be another problem with my configuration, not a general thing with the maxlength-option.
Good to now - thanks a lot.
I was able to reproduce the behaviour: I have just installed a fresh starterkit with Kirby 3.9. Although I have extended the length of the slugs to 258 characters in config.php, it is shortened to 128 characters. There is also no warning that the slug is too long. In Kirby 4 it works as expected. Perhaps it is a (not yet discovered) error? Therefore, I hope for feedback from @texnixe , if there is another setting for Kirby 3.9.