More than 3 years. Circa April 2020.
They added it to that upper right corner around the time of this seller update:
https://www.ebay.com/sellercenter/resources/seller-updates/2020-spring/service
But they changed it this week to look like a button with an outline. Before that it was just a blue text hyperlink.
GLORIOUS!Confused about the switch to eBay discounted shipping? Read
this discussion to make an informed decision about opt in / opt out.
