This is a feature of iPadOS 13: the browser can either report itself as an iPad or as the desktop version of Safari; it does the latter by default. iPad users

This is a feature of iPadOS 13: the browser can either report itself as an iPad or as the desktop version of Safari; it does the latter by default. iPad users across the board now use a best in class browser and expect a best in class experience. Apple is protecting its users from subpar websites written by subpar developers, especially those who rely on lazy tricks like UA parsing.