Why does Plex remove "-" in a Movie Title?

For example:
If I enter the title “London - Restaurants” to my movie, plex will remove the “-”.
After a few days, we verified that Plex removed the “-” and we came to see the title thus “London Restaurants”.
Even if you block the Title, Plex removes the “-”.

see your other question on Plex not showing release dates.
You should set your home video library’s media type to Personal Media. Plex removes the - and some other special characters from the media title when preparing to match the film against the respective online database (e.g. The Movie Database). This doesn’t happen with Personal Media and if I remember correctly, Plex will therefore also keep those characters in your media name (even without further editing) – at least I’ve found some of my personal media with - or punctuation in the title (and I don’t remember having those titles edited.