For posts in src/data/blog/ (root level)

Why two ../?
src/data/blog/your-post.md
↑ ↑
.. .. → src/assets/images/...
- First
..goes fromblog/todata/ - Second
..goes fromdata/tosrc/ - Then into
assets/images/...
Common mistake
Single ../ would be wrong — it would look in src/data/assets/ which doesn’t exist.