Where can I find past theme versions?

My page headers used to match on my pages and posts, but since the March 11, 2021 update, they are now extremely different, with the header on my posts not displaying the search bar, and the logo moved over to the right instead of floating left. I can look at all these posts on the way back machine, and everything was looking as expected prior to this update.

The page I need help with: [log in to see the link]