New API - The ThemeDb has moved from github to deckthemes.com, providing a much more streamlined submission/review process, and A full-featured web ui for browsing/interacting with themes.
Theme filters now show the count of themes for each filter.
Only the first 50 filters of a given query are loaded initially, with a "load more" button to grab more.
New order have been added, "Most/Least Downloads" and "Most/Least Stars"
If you create a deckthemes.com account and link your deck to it, you get:
Starred Themes: You can star your favorite themes and access them easily from a separate "Starred Themes" tab
Submissions: If your account has permission to view submissions, you will be able to view active submissions and download them to your deck without needing a computer.
New Theme.json Features
A patch/inject can now inject a specific CSS variable as opposed to a full CSS file.