What are some of the worst tropes in writing and novels?

A trope is simply a story-telling convention that all writers have to use to some extent. They become cliche when they become tedious, and what is cliche in one genre is required in another. You'd be better off looking at the cliches from each Genre.

But the ones I dislike in all are:

Love triangles

Weak, flat characters

The "strong" female character written to the point she has no weaknesses or does but they never seem much of a problem. She also has a horrible personality and tends to have a manly quality and fems think this makes her strong. What they don't realize is, they are saying a woman has to be like a man to be strong.lol

Drop dead gorgeous characters who just moan about how plain or ugly they are

Characters who ate just there to serve the plot and are moved around like chess pieces with no life beyond it.

Contrived plots

There are so many it's impossible to list them all, so I'll just mention the ones that especially bother me.

Opening with a dream.

Having some scene turn out to be a dream.

Opening with the character waking up.

The character describing what they see in the mirror.

A pretty woman who has no idea she's pretty.

People who have no responsibilities and drop everything to enter into an adventure, solve a crime, or begin a vacation romance.

Characters who have no lives outside the story.

Deus ex machina, whether it's a god or an astonishing coincidence.

Characters who do not regularly work out but are able to run a long way.

Characters with no training who are able to fight well.

Characters who have a pet, then leave for adventure or whatever, pet never mentioned again. (I always imagine it starving to death.)

Characters who drive drunk or otherwise put people at risk without a second thought.

Characters who see their friends onto planes or carry a gun past TSA.

Characters who know how to get a passable fake ID.