The only issue they mention is browser page text search not working on rendered file view (blame).

The feels legacy conclusion doesn’t make any sense to me.

GitHub is not the only platform implementing virtual scrolling, partial rendering of rendered files. There’s a reason they do that: Files can get big, and adding various code highlighting and interactivity costs performance. It’s not a local code representation and rendered canvas. It’s rendered into a DOM and DOM representation, with markup and attached logic. Which at some point quickly becomes very inefficient or costly.

Not being able to use the browser text search is an unfortunate side effect.

I consider it a worsening modernization/feature addition. That’s the opposite of legacy. We’re moving forward (in a bad way), not stagnating.

When I click Blame, and then press Ctrl+F, it opens not my browser text search but the in-page in-file search. It works for me. (Not that I always use that search or like it.)