Have been reading this thread with interest, and if I may make a few comments:
Blocking or otherwise disrupting vpn traffic is not uncommon. This can be accomplished in a number of ways, and as we move more and more towards infrastructures being built and defined in software rather than on bare metal appliances and devices it becomes more effective as it tends to offer more opportunity for the administrators to be creative and to adapt within a framework that offers far more possibilities.
One example (although slightly different in implementation) is the way the bbc do it for their own CDN's. Whilst this is perhaps not directly comparable to someone like an ISP doing it within their upstream networks it ends in a similar or identical result and frustration for the person at the client end of things trying to watch a beeb broadcast over a vpn connection that is being tampered with or otherwise outright rejected by the CDN. You might typically see many of the commercial vpn providers continually updating their services and encouraging their users towards using ever-changing servers if they wish to access the likes of the beeb (and ntflx who also do similar things with their CDN's).
When this type of thing is done by an ISP it is often difficult to overcome, because we as end users have no control over what an ISP might choose to do with traffic in their upstream networks. That said, even with so much money at stake (for the likes of sly for example) they do still operate within some constraints and parameters. First and foremost, we need to understand that any ISP supplied appliance (ie your router that your ISP gave to you) is for the ISP simply a control and surveillance device and is a key and instrumental part of how they deliver their services to us. So, first order of business is to never ever use an ISP supplied appliance. Next order of business is to not use any ISP's DNS servers. Just now, I personally would recommend Cloudflare's 1.1.1.1 as the primary DNS resolver on any network or device. That being said, be prepared to review that on a regular basis, but right now, 1.1.1.1 is IMHO blowing just about everything else into the weeds in terms of accuracy, cleanliness, completeness and outright speed of performance. Third, if you don't need IPV6 for anything in particular then just ignore the nay-sayers and switch-off/disable IPV6.
We live in a world now where more and more software 'bots are being used for vast ranges of activity. I am sure that the admin's here will see allot of evidence of this here in this forum where "people" build a set of user credentials simply as part of an SEO activity as a way to try and build backlinks to their own or an affiliate site. Simply put, someone set's a 'bot loose and it will be able to find forums like this one and then within a few seconds create a dozen or so user accounts with neatly populated fields in the profile. The thinking behind this is that when this is done and then crawlers (another type of bot from search engines) come along the apparent credibility of the target site gets lifted up the batting order because people are seen to be linking to it.
Now I appreciate that this paragraph looks like I an drifting off of the thread topic, but just consider this for a minute - - - If you can set a bot loose to do that on things like forums, then why can't you use a bot as a means of recognising particular classes of content or a type of traffic (say for example vpn traffic using UDP Port 1194) and in turn making a decision as to whether that traffic be allowed to pass onwards or alternatively dropped altogether, or alternatively interfered with so that the end user's experience is rendered useless. Such a bot could also be designed to learn and remember from it's experience too, so if for example we simply change out port numbers that we use, then the bot should be able to see a common footprint in the nature of the traffic passing by.
Add to this, outright offensive attacks on IPTV servers and CDN's and the people who operate the types of services that we might subscribe too have rather allot to deal with if they are to have half a chance of offering a service to their customers.