It may also be useful to dump random thoughts on an issue for later expansion and review. Like I'm starting a side project or learning a new language or whatever and so I'd dump stuff on the relevant issue/epic.
Bonus points for self-hosted.
EDIT: also useful to track hobbies and repair stuff. I'm into woodworking, electronics and mechanical repairs so having every task organized may free some brain cycles to do better work.
Trello is flexible and simple enough to work well in a number of different capacities, so it's a great multitool for some. Especially if you're naturally geared towards organising your life in this methodical kind of way.
It's a one time payment of $10 for the self hosted version.