Hey! Thank you for the detailed steps for reproducing the issue. To clarify, in step 2, do you type github.com/typescript in the address bar and hit enter? This should result in a new tab with the desired URL.
DavidNechiforel Press Cmd+1 to return to the pinned tab
Current result: The tab still shows github.com/typescript
Following these steps, I am able to reproduce the issue of the pinned tab having a URL that still says github.com/typescript but the page that is loaded is github.com/rust. Does this match your experience?

If not, could you share a screen recording of you reproducing the issue?