Kabsetz post #9 in the linked thread describes it as barrel distortion (angular magnification distortion)
www.birdforum.net
To add some perspective - I’m slightly sensitive to globe effect while panning - the ELs make me uncomfortable while the NLs and SFs do not. However, I found total distortion from the 30-60xWA while panning more pronounced than any binocular. In addition, the distortion is far more pronounced at 30x than at 60x. In contrast, I can pan to my heart’s content with the 20-70x eyepiece without noticing any similar effects.

Is really Meopta S2 82 + 30-60x as good as the Nikon, Leica, Kowa and Swarovski..?
I am considering to order a Meopta S2 82 HD with 30-60x eyepiece to test it against my Nikon ED82. My wish is to have a spotting scope with high optical quality and a zoom with a field of view equivalent to Nikon's fixed eyepieces. I have a friend who is interested in buying my Nikon ED82 with...

To add some perspective - I’m slightly sensitive to globe effect while panning - the ELs make me uncomfortable while the NLs and SFs do not. However, I found total distortion from the 30-60xWA while panning more pronounced than any binocular. In addition, the distortion is far more pronounced at 30x than at 60x. In contrast, I can pan to my heart’s content with the 20-70x eyepiece without noticing any similar effects.