Is setting FireBase registration token as WebView useragent a bad idea?

Question

here's the code i'm using

FirebaseMessaging.getInstance().getToken().addOnCompleteListener(task -> webView.getSettings().setUserAgentString(task.getResult()));

is it against ToS or insecure or anything like that? can it cause a problem? and more importantly, is there a better way?

with this, i can easily get tokens for my users and send notifications to a specific user automatically from my flask app.