For notetaking, anything other than fleeting notes should be entered into a future-proof system. The most future-proof system of all is plain text.
Plain text is durable. This king of the Durable File Types Tools may come and go, but every tool can work with plain text. They are the most widely openable file format in existence. You can open plain text files (and their semantic offshoots, like ".md" files) in almost anything. Even the console itself can display them.
Tools like the Notetaking platform "Obsidian" were built around plain text files for this very reason.
For formatting, you can utilize Markdown. Data can be stored via CSV, JSON, YAML, or XML.