This conversation has been merged. Please reference the main conversation: Photoshop CC 2019: Transform/Resize is constrained by default - Want ability to go back to legacy behavior
After I tried and sweared for half an hour, I found:
New in Photoshop CC version October 2018 (Version 20.0)
When converting most layer types, such as pixel layers, text layers, bitmaps, placed smart objects, simply drag a corner handle to scale these layer types proportionally. If you hold down the Shift key while dragging a corner handle during conversion, these layer types will be scaled non-proportionally.
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