maybe the browser version isn't fully complete, or there might be a thing with css, bad browser specialities, just a bug in the webpage (did you check if it does show up in page source plaintext maybe?)
i would see the warning "bound to a specific non-changeable service as a good thing, as it would promote completely-free apps like (i think) fluffy chat, which does neither depend on a specific matrix service nor on a specific push service (i.e. it uses ntfy for push when installed, and if i choosed to use my own instance it would - i think - use that instead of the default ntfy.sh)
in theory everyone could run something like osm and in practice this could come in very handy in the future one day, but currently IMHO only one osm exists, so maybe its not that bad for an app to be bound to it, but its always good to know if an app is bound or free to choice, same i would like to know if its maybe multi-account (which fluffy-chat is), but single-account-apps are so very common and thus this is not seen as an anti-feature which is completely ok for me.
but also in this case here the app is not only bound to osm, but to two other non-changeable services too, thus the warning is due even if label-app-bound-to-label-service would NOT be considered an anti-feature.