This just changed in the most recent update to Premiere 24.6.1 (Build 1). Normally, if the timeline is the active window, and then you click on the "Export" tab in the upper left next to "Import" and "Edit", it knows you want to export the active timeline. Right now, it selects whatever clip or sequence you have selected in the Project bin. So clearly, this is not intuitive and should be reverted back to the way it used to be.
Running MBP 2021 M1 Max, OS Sonoma 14.5