[Bug]: Incorrect Handling of Double-Encoded URL Parameters

[polamoros]

What version of React Router are you using?

6.22.1

Steps to Reproduce

• Define a dynamic route to capture branch names, using the pattern /:branch.
• Encode a branch name that includes slashes (e.g., fix/my-awesome-fix): fix%2Fmy-awesome-fix
• Encode the encoded branch name (needed to use it as a URL param): fix%252Fmy-awesome-fix

Expected Behavior

Handle the double-encoded parameter by decoding it once, transforming %252F back to %2F, and preserving the slash as encoded.

Actual Behavior

The double-encoded slash (%252F) in the branch name is decoded twice, converting it directly to /, which misrepresents the original branch name (fix/my-awesome-fix instead of fix%2Fmy-awesome-fix).

Anything else?

I was able to reproduce the issue on versions 6.19 and 6.20, so it's not related to https://github.com/remix-run/react-router/issues/10814#issuecomment-1930026232, which I initially thought might have been the cause.

[skyrpex]

Exactly. I don't fully understand why would the router decode the params until there's no special characters in it, instead of just decoding once.

[Zboule]

Issue reproduced in version 6.22.1

Could the URL be decoded only once ?

[dishu5312]

Facing same issue on version 6.22.1.

Any updates on this?

[almostintuitive]

Unfortunately we're bumping into this as well. Is there any potential fix?