It can be described as "weak" or "lazy" to write basically anything where you can rely on conventions of the genre or your own experience and don't need to do research or worldbuilding.
Fantasy can be lazy if the person just goes with the most generic, bland fantasy setting possible. Like I could construct a super-lazy fantasy story so easily. "In the Kingdom of Concordia, ruled by the good King Albert, a young shepherdess named Mia discovers she is the long lost twin sister to Princess Alimere when she is saved from assassins by a dashing half elf called Kayde. Can she uncover the plot and find love?" I came up with that literally just now. Then I'd just throw in all the basic crap. I'd grab some 3D castle assets off the Clip Studio Materials marketplace, and my setting would have elves in it, and the elves would be skinny humans with pointy ears who are aloof and live in the woods and do magic, and it'd have dwarfs who are short, grumpy, have beards and Scottish accents. The clothing would be kinda-medieval, but not researched at all and modified to suit modern tastes. Lots of tunics, pants that look suspiciously like jeans tucked into high boots, nobody wears a hat, everyone has modern hair. There'd never be questions about whether monarchy is good, it'd just be like "so long as the king is good, the land flourishes", and I could probably bang it out really fast.
But you know what I could also bang out really easily? A totally uninspired modern office Romance. Lucy is an ordinary office temp working at one of the world's biggest fashion magazines. She dreams of becoming a fashion designer, but can never seem to catch a break! But then one day, she gets stuck in the elevator with a handsome stranger and falls head-over-heels for him. Little does she know, the man she had a brief, steamy flirtation with is Asher Chance, the son of the CEO of the whole company and her life is about to get turned upside down! Okay there we go, just download some basic office assets, a bedroom, some bars and restaurants... doesn't matter if they don't clearly resemble a specific city because the audience won't care and I'll never openly say what city they're in. Office life should be easy enough because I've worked as an admin myself... Yeah. Nothing too taxing there.
If you're just following the typical storybeats of the most generic examples of a genre, and you take absolutely no risks with your setting and characterisation and just base it on either stuff you've done yourself, people you know IRL or archetypes of that genre and stuff you've seen before, basically any sort of story can be low-effort. High school coming of age, slasher horror, isekai villainess fantasy-romance... they all have conventions you can 100% lean on, or the possibility of trying to subvert expectations and strive for originality and tight, surprising storytelling.