URLs are definitely encrypted. What can be sent unencrypted are domain names and IP addresses. Which is not a problem when the host name is ‘youtube.com’, but is a bigger problem if it is ‘the-terrorists.com’.

But all this is available in desktop Firefox. Partially built-in, partially via add-ons. The mobile version is very limited.

Making most of the internet dependent on ad revenue was a bad idea in the first place.