In other words, it's not great that this is possible, but nowhere near an immediate and present danger to anyone except a very very small group of people doing very very specific things.
If you're in that group, you'd already known you are. You'd have someone to ask about this. And you'd almost certainly be using some other tools to anonymize yourself anyway.
If that's not the case, then this is almost certainly not something to lose sleep over. Signal remains a safe choice of a secure IM. 👍