If you don't know what crabs in a bucket mentality is, it's basically when one crab tries to escape the bucket, the others pull it back down.
In people terms, it could be your colleague getting a promotion instead of you, or your friend getting a new car. You may respond with envy and try to diminish their achievements rather than celebrate it.
I have certainly experienced this in the past, and put in a lot of self work to get past it.
I also feel like it's a bit more prevalent in the UK than other places.
Perhaps you can all prove me wrong?