When I first heard about the tunnels I got no context with it and thought maybe they were building an underground access to another building (and as a guy who works in the Middle East, nothing beats underground access to other buildings during Summer, let me tell ya), but then I went on twitter and I'm reading some of the weirdest blood libel stuff.
I'm not gonna shed any tears for this particular group though, as there's an anti-zionist twitter group that explained this group's ties to Israel; apparently they're both anti-zionist but pro-Israel, in that they detest that Israel is secular but still support them because they want a Jewish state (religiously Jewish that is; they don't merely want a state of Jewish people). They've held meetings with multiple Israeli prime ministers including Benjamin Netanyahu (https://twitter.com/TorahJudaism/status/1744728504829428196).
From my understanding, at the core it seems to be as simple as the tunnels were built to facilitate the illegal expansion of the synagogues space, with a whole bunch of strange internal hasidic sectarianism involved on top of that to make it sound more complex and much more bizarre than it probably actually is, those involved being hasidic of course makes it inherently wacky for much of the online world.
yea there's a large community of chabadniks in crown heights. that's what all the stickers declaring MOSHIACH IS COMING are about. They specifically think that Menachem Mendel Schneerson was and is the messiah, and will reveal himself soon to usher in a new era of peace, wisdom, and piety.
yeah, i think this ties in and a lot of people initially misinterpreted it, because on the day it was revealed a lot of posts were about how they used the tunnels to evade covid rules and enter the synagogue secretly to congregate
no, they're much more isolationist than evangelicals. their religious conservatism is largely directed at their own families. similar problems with racism but a very different phenomenon otherwise.