It was Clearcast that rejected it you can see the reasoning here [0], seems to be mostly that it implies VPNs facilitate criminal activity and "irrelevant to the average consumer’s experience with a VPN". Either way they gave a real gift to the marketing team in rejecting it. Every person in advertising dreams of having to write the phrase "our banned ad" even more perfect when the ad was about tracking/censorship.
[0]: https://cybernews.com/news/and-then-mullvads-anti-surveillan...