Client Secret with umlaut is not encoded

I defined a client secret with umlauts in my web service (using OpenIddict for OAuth2 authentication in the service).
When authenticating with SwaggerUI, the login is rejected:

Using Restfox, it works without problems. And Restfox gave me a hint: the request body is url encoded:

client_id=myservice&client_secret=%C3%B6rotkg%C3%B6odrtbjpo%C3%B6id%C3%B6woi4mfwp4wf3tgwp94w9&grant_type=client_credentials

So, I entered the client secret in SwaggerUI the same way, and it worked!

Thus I assume that SwaggerUI does not encode the client secret when sending the request, and I think it is a bug.

This is my original client secret (which fails):
örotkgöodrtbjpoöidöwoi4mfwp4wf3tgwp94w9
And this is url encoded (whichs works if entered like this in the "client_secret" field:
%C3%B6rotkg%C3%B6odrtbjpo%C3%B6id%C3%B6woi4mfwp4wf3tgwp94w9

I use Swashbuckle (https://github.com/domaindrivendev/Swashbuckle.AspNetCore) which currently bundles SwaggerUI 5.17.14

Start by reproducing the OAuth2 client-credentials flow in Swagger UI using the non-ASCII client secret described in the issue, then inspect the outgoing request body and compare it with the Restfox example. Done means Swagger UI sends the client_secret URL-encoded so authentication succeeds without manually encoding the value.