Notepad3. Looks and behaves like Windows notepad but with syntax highlighting, regex search, optional dark theme, lightweight native-built code that launches instantly, and all the other modern features you expect.
I now run entirely on Linux.
But before that I used Notepad++ for 12 years and finally switched to "Notepad3" 2-3 years ago. If you use an IDE for heavier tasks, "Notepad3" is excellent, much faster and cleaner than Notepad++ and other Windows editors.
Presumably it's called Notepad3 because Notepad2 was taken?
I haven't tried Notepad3, but I've used Notepad2 for years and preferred it to Notepad++. Great little editor. Bonus: no installation needed (useful if you don't have admin privileges on the machine).
https://www.rizonesoft.com/downloads/notepad3/