The reverse. Argo gives better peering than any paid plan. Its the reason for the product‘s existence. They can use more costly peering that they couldn‘t use with their free egress model.

Can you share some anecdotes?

You don‘t have to get the Pro plan to solve the Deutsche Telekom issues. You can also use their Argo product for $5/month - but only makes sense if your egress costs wouldn‘t exceed the pro plans pricing.

The reason for that is that all nodes talk p2p to each other. There is no central communication server like with many other vpn solutions. So even if Tailscale would go down for days you won't have any downtime between your nodes.

I believe they try to indirectly say they are using SerpApi or a similar product that scrapes Google search results to use them. And other big ones use it too so it must be ok...

That must be the reason why they limit the searches you can do in the starter plan. Every SerpApi call costs money.