While Eurostar did say officially that the reason for the closure was Covid and the resultant low passenger numbers, I think it is reasonable to presume that they will be looking at the impacts of Brexit with very close interest. Although we may never know for sure how much impact (if any) Brexit has had on the decision, the 2022 re-opening date enables them to see the impact of both Covid and Brexit before deciding to reopen.
Also, I’m not talking about Eurostar having a service to Germany, I’m talking about the 20-min connection at Brussels, which is used by many, and I have read that DB trains are occasionally held for a few minutes to enable people to change. It is a useful facility, and saves people a lot of time. I have made it before, but it took 10 minutes, meaning just 10 mins to spare. A customs check will make this take longer, resulting in people easily missing that connection.
First world problem? Well all problems with international travel could be considered a first world problem. Also, it’s not just tourists who use Eurostar, it’s also business people, who may be travelling between London and Frankfurt for example.