URIError when viewing User Detail page of specific Cognito user

For testing purposes, I created a user in a user pool with the User name !@#%&ñ;\t\r\n. The user was created through the AWS Cognito API. When I went to view the user's detail page by clicking on the name of the user in Cognito, I got a blank page, along with the following error in the console:

URIError: URI malformed
    at decodeURIComponent (<anonymous>)
    at main.js:1:53784
    at Array.map (<anonymous>)
    at i (main.js:1:53669)
    at Pr.e.map.t (main.js:1:279386)
    at ss (vendors.js:2:808632)
    at Ka (vendors.js:2:860757)
    at kl (vendors.js:2:848035)
    at Tl (vendors.js:2:847963)
    at xl (vendors.js:2:847826)

If I instead try to open that page in a new tab, I get a 400 Bad Request page.

My guess is that the backslashes in the username are not being escaped correctly. This appears to be a Cognito bug. I couldn't find any better place to report bugs than here, would be happy to post somewhere else if there were a better place.