I don't believe Verizon would "discourage" Tor. It would either block it completely, or continue to allow it.
The tiny percentage of Tor users don't concern Verizon. The miniscule loss of advertising revenue isn't as big of an issue as the bad publicity that messing with TOR would get them from media.
VPN users might be a thing they get concerned about, at some point, but I'd expect them to come out with a VPN service if that was the case.
So I expect this will be traced to some kind of incompetence or error, not a deliberate effort.
The reason Cloudflare originally flagged Tor nodes was because 99% of the traffic over them was malicious. Cloudflare cared to make an alternative solution to it, but most presumably would just let a perceived malicious IP remain blocked.
It's probably a bad DOS protection mechanism, that has either the inbound or outbound net set too wide. Not uncommon, though a PITA and hard to distinguish from censorship (and why botnet blocklists should be public)
The tiny percentage of Tor users don't concern Verizon. The miniscule loss of advertising revenue isn't as big of an issue as the bad publicity that messing with TOR would get them from media.
VPN users might be a thing they get concerned about, at some point, but I'd expect them to come out with a VPN service if that was the case.
So I expect this will be traced to some kind of incompetence or error, not a deliberate effort.