Handwritten notes naturally use more storage because each pen stroke is stored as detailed vector-based data (similar to an SVG), rather than simple text. This allows your handwriting — including every curve, angle, and pressure change — to be reproduced precisely. Typed text, by contrast, is extremely lightweight since its shapes come from pre-installed system fonts, so only the character codes are stored. Handwriting content can be roughly 10x - 100× heavier than typed content.
In addition, please note that:
Notes in your Bin still count toward your total storage until they’re permanently deleted.
Custom templates you’ve created or imported also occupy storage space.
If you’ve recently emptied your Bin, it may take some time before the storage usage reflects the change.