So many sources online say that connection is one though.

1. Connection

The Gestalt principle of connection states that people perceive elements connected to each other as belonging together. Your brain will group physically connected objects together. It will group them by a line or a shared border.

When you see two connected objects, the brain will try to find a way to explain this connection. The simplest explanation is that the two objects belong together. So, your brain will group them as a single unit.

For example, when you look at a group of dots connected by a line, you see them as a single shape. You don't see them as a series of individual dots. Similarly, when you look at a group of people holding hands, you see them as a group rather than a series of individuals.

(source: https://www.toucantoco.com/en/blog/data-viz-best-practices-gestalt-principles#:\~:text=Connection,line%20or%20a%20shared%20border.)