What problem does this address?

The current single column layout of pattern thumbnails in the Patterns tab of the Sidebar Inserter makes it arduous to scroll through and view many patterns at once, especially if there are many patterns within a category. The category dropdown menu requires two clicks to change the category view which feels a bit clunky and slow when browsing patterns.

What is your proposed solution?

This proposed direction displays patterns in a two-column masonry grid (to accommodate the varying heights of the designs) with category filter links so users can immediately get a sense of the breadth of categories offered and jump between category views with a single click. Here, I’m pulling example categories from WordPress.com where there are far more (~14) than in the Core Editor (~5)—both may have an extra category named after the current active Theme if there are patterns registered by that Theme.

These category filter links can be iterated on further once we’re able to offer multi-select category filtering in the future when pattern loading performance is optimized.