I moved to a small town 6 months ago and had a really nice birthday party the other day, with all the friends I've made here (obligatory disclaimer: yes, it followed Covid guidelines). It was a themed cocktail party; a few guests brought alcohol, some played cards, it was a blast. I certainly wasn't expecting any gifts and the 2 or 3 that I did get were thoughtful and really appreciated. One curious observation I made after the event was that of the three groups of friends I invited, most of one group brought gifts/cards/alcohol/ice/cake and no-one from the other two groups brought anything. It certainly wasn't a means thing, as some of the poorer guests brought gifts and many of the wealthier one brought nothing (one of them even invited us to their place last week and we had to pay for food!). I'm not the sort of person who cares what a gift is worth (one of the cheapest gifts I received was the most thoughtful, and someone just gave me a card with a really lovely message). I do believe, however, that its the thought that counts. Is gift giving at birthday parties still a thing or a dying trend?
tl;dr
Is it still customary in 2021 to bring a gift/card/alcohol to a birthday party?
Depends on the size of the party and how well you know them. If it were a dinner and they were cooking, yeah bring a bottle of red.
If it's a bbq, bring your own food and grog etc.
If it's a close friend then you'd know if they want/need something. A new friend/acquaintance I wouldn't bother. Just make sure you're cost neutral for them.