They do a bunch of DNS stuff but their main product is a proxy that tests traffic and blocks malicious connections e.g. Ddos attempts, bot traffic etc. It also distributes your website over DNS to reduce loading latency when people want to connect to it from far away. It works great which is why people use it (it’s tough to block specifically malicious traffic) but it’s also a proprietary US company that needs to basically take over your front facing website to do what it does, and since they analyse traffic they also get to keep a copy of it. There’s been issues in the past with them collaborating with law enforcement no matter what their clients might want. And of course if their service goes down like it did today none of their websites are available anymore

they sit in front of websites to protect them from ddos and ai crawlers and the like. as part of that, they are given the encryption keys for the website so they can scan for unsavory traffic and likely they give a copy of the data to homeland security