Matt from Fanthatracks.com sent along some pictures of a bubble variant found on the Hasbro 3 3/4" Retro Collection Yoda action figure. The regularly available version has a standard bubble, while the newly found version has a shorter and more accurate bubble compared to the original Kenner Yoda figure from the 80's.
The Empire Strikes Back wave of Retro Collection figures was released in 2020 as a Walmart exclusive in the United States (look at the full Star Wars Retro Collection line-up), and we don't know yet if more of those figures will be made available through the Fan Channel in the future.
You can see the newer, shorter bubble on the left with the common version on the right
You can see the newer, shorter bubble on the top with the common version on the bottom
Thanks to Matt for sending those pictures through!