By design the redirects passes through the query string. To stop this happening, you can add a query string as demonstrated in [Support Guide] Making redirects work for you - troubleshooting and debugging
/MyCap participantCode=:id /MyCap/:id?redir
Whether this solves the issue with Android Webview I cannot say. The only other way to remove the query string (that I am aware of) is using JavaScript on the front end.