I wasn't all that far into Dragon Age: The Veilguard when I realised I'd been locked out of a sidequest unexpectedly. It was after the first significant event in the game where you, of course, have to make a big decision that has some longer-lasting repercussions. But if you're not paying attention to your quest log, you might not notice that some quests disappear into the completed section with a little entry above them saying something along the lines of "You can no longer complete this because this event has happened".
This occurs throughout the game, and in-particular, affects faction and companion quests—essentially the two most important quest types for if you want to gain allies, faction reputation, or even romance a specific character in the game. One to look out for in-particular is Taash.
