Vim can automatically insert comments on pressing enter. To enable/disable this,
```vim
set formatoptions-=r
```
(see [vim.fancom.com](https://vim.fandom.com/wiki/Disable_automatic_comment_insertion) and [vi.stackexchange](https://vi.stackexchange.com/questions/1983/how-can-i-get-vim-to-stop-putting-comments-in-front-of-new-lines)