I much prefer to trust an implementation over someone's word. I use Signal because I agree with their stated goals, and their implementation seems to align with those goals. I don't use Facebook because their policy is awful in the first place, and implementation is nonexistent. Kagi is in between. I am happy with their policy, but their implementation is lacking. This wouldn't be a problem, but they don't seem to admit that their goals are fundamentally in conflict with their mode of operation.

This is the first item on their FAQ:

"Our goal is amplify the web of human knowledge, creativity and self-expression and provide the user tools to fight against the web of greed, ad-tech and user tracking."

To pretend that company policy is the best way to achieve that goal is insulting. We will never have an ad-tech and tracking-free future without technological measures. Offering a service on the basis of "Pay with your money, not your data" is a fantastic step in the right direction, but obviously not enough.