I blame the countless, badly written, articles floating around right now about how they took up brewing during lockdown.... Every single one of them that I have read talks about boiling grains in the bag etc etc at some point, almost like they're confusing brew in a bag with boil in the bag....
Brews go wrong sometimes, shame it was a kit as they cost more than just buying the ingredients usually, but heh you live and learn. Rather than running out and buying John Palmer's How to Brew (an excellent book, but massive and goes into a LOT more depth than you need initially), I'd actually recommend either Brewing Britain, The quest for the perfect pint, and how to make it by Andy Hamilton (my first choice, as not only does it tell you all the different methods of brewing, with recipes etc, but also goes into the history a bit, and also gives commercial examples for the various styles discussed. Really enjoyed reading it), or good old Home Brew Beer by Greg Hughes if you want something a bit more direct. Both excellent books for the beginner, where diving straight into John Palmer's How to Brew is likely to give you a migraine.... lol Heck, at a push there's even Brew by Jame Morton, but you'll end up breaking the bank with the quantity of hops in his recipes.... On the plus side, he's very BIAB/stove top oriented. Whichever you chose though, DO either beg, borrow or buy a book and read it.