Avoid auto connecting to free Xfinity wifi on Xfinity mobile

Hi, I have a Google pixel with Xfinity mobile, and it keeps auto connecting to free, unsecured xfinity wifi Networks. How do I prevent this from happening? Each time I manually disable auto connect on one Xfinity mobile wifi network, it will still auto connect to the next one I am in range of. This is a security concern for me because it seems most of the networks are unsecured.