Upgrading to Webform 6.1.1 removes custom query parameters in confirmation URL

Problem/Motivation

It seems like the recent change in https://www.drupal.org/node/3247813 creates a regression when you want to include custom query parameters in the confirmation path. These are easily available as tokens in the Confirmation URL settings but are now removed.

EDIT:
I played around with the settings and noticed that if you add a forward slash to the beginning of confirmation URL, it then works correctly. Maybe it might be beneficial if there would be a validation for the confirmation URL or at least a help text to say that of course it needs to be a valid route.

Original issue:

At the moment I have the following query string parameter in a custom confirmation path:
confirmation?submission_id=[webform_submission:sid]

With version 6.1.0 it works correctly but with 6.1.1 it replaces the custom query parameters with the original query parameters.

In our case this creates a regression since we want to get the created webform submission ID in the confirmation page and fetch data from it.

Could this be made as optional setting that original query parameters are replacing custom query parameters?

It seems like jrockowitz did test it should keep the query parameters intact but it seems like its not working.

If I test this with the attach webform I get redirected to the following URL:
form/test?token=uFUjTjf3aaYH5Ljpv4B9yjqmWYiKWGpKmlqRmHbOtAg&webform_id=test

But at the same I get the error:
Confirmation URL confirmation?submission_id=784 is not valid.

So it does seem like it knows the submission_id query variable but still redirects to a different query parameters with the token and webform_id in the URL.

Steps to reproduce

Attached is a webform with a confirmation URL with query parameters. These are removed when the form is submitted and replaced with new query parameters.

Proposed resolution

The query parameters should remain intact if they are available in the confirmation path or these should be optional in the confirmation URL settings.