This has happened multiple times in the past with similar aggregators. I will be surprised if it does not happen again. But good luck. I want products like this to exist.

Yes they can! But it's unlikely they would all do it at the same time.

t2bot.io hosts a Discord bridge and to my knowledge it is officially allowed by Discord (else they could not have more than 100+ bridge users).

The Discord bridge you are talking about here is a Bot which is officially allowed by Discord, however the Bot APIs have serious limitations that make it unsuitable for full bridging (which is basically making a Discord client). For example it can only be used in "channels" and needs to be added to each "server" by an admin. This means that it is hard to use in servers where you are a guest and you can't use it in DMs and non-channel group chats.

I assume they are offering a "puppeting bridge" which means it acts as you, however this means that it is using unsupported APIs and Discord has been known to ban accounts for this.

I think it is pretty disingenuous to put the Discord logo on the homepage without pointing out those caveats.