Are you seeing the same thing if you click that invite link yourself?
If it’s happening on both yours and your client’s systems then it’'s likely either a bug or custom code in the page that’s interfering.
It looks something like an encoding issue so I would not be surprised if it’s a bug due to some work on the upcoming localization capabilities. For that I’d contact support.
If it’s only happening on one system, I’d try disabling browser extensions.