Finder has trouble mounting folders with special characters

Question

I know in general it's bad to name files and folders with special characters.

As an example:

I created a folder on our NAS and named it test% so far so good, no error on creating it like "you can't name a folder like this" (I remember this came up on Windows or I believe also on mac with some characters but can't figure out which right now)

Now I copy the smb:// path of it via command + I and make it a clickable link in an email.

So the path is for example smb://Server/folder1/test%

Finder opens and a small windows comes up "Connecting to smb://Server/folder1/test%".

When I do this, the loading bar is jumping back and forth forever and nothing happens.

When I do the same thing but with a folder without a special character: smb://Server/folder1/test it works and Finder can mount the folder as expected.

Is this a bug? Can I fix it somehow (besides stopping to name folders and files like this)?

My Mac is currently running Big Sur 11.3.1

Quick edit:
I tested some more special characters like $, &,. (they work). / didn't and also I got an error that this folder doesn't exist (although it does).
But % displays the correct folder name in the loading bar but doesn't do anything.

Answer 1

Without having to learn the entire illegal character list for every OS, it's best to train people to an easy subset of these rules…

Alphanumeric only. No umlauts, etc. No spaces, use underscores.
You could probably make a call on Capitals, most OSes are case insensitive, so it shouldn't matter.

Don't let them use edge cases & you won't have to fix them;) This is especially important if you have multi-platform access, as illegal characters on one OS may not be on another.
I'd make a rule on replacing umlauts too, decide whether Müller should become Muller or Mueller & stick to it - that way people will not need three guesses to find an otherwise known name.
Using underscores with no spaces just makes paths simpler - no-one has to guess whether they need folder name folder\ name folder%20name or "folder name" to find something, it's always folder_name.

% is a URL escape [encoding] method as seen above, %20 means space - best to be avoided for names in URLs.