Troubleshooting Bridges to WhatsApp and Signal

Hi,

I'm new to Matrix and only a user. I don't own a homeserver.

My goal was to bring family and friends to Matrix. Therefore I wanted to test a Server with bridges to WhatsApp and Signal so they could use one App to communicate with most of their contacts.

I joined nope.chat and use Element and Fluffy Chat as Clients. I added Bots as Bridges for WhatsApp and Signal.

The bridges work but have some flaws. So I can't recommend them to my family.

One of the concerns: Is it safe to use bridges at all? Who can read what on the server if I am using a bridge?

Second Concern: I keep getting invitations to a WhatsApp-Community I have never joined. I have declined the invitation but it keeps popping up. If I wanted to ban this chat I would have to ban the whole WhatsApp-Bot.

Any thoughts on that would help.