(one of Yay's first appearances) they are shorter than both Bubbles and Emily.
Yeah, but Bubbles also lost an inch or two after she took off her armor and after the first instance, Bubbles and Yay have yet to meet again; but we do have another height reference, her Royal Highn-ass Faye.
Fay&Spooky where SpookyBot's nose is at the top of Faye's forehead then
Fay&Yay where Yay's nose could poke Faye in the eye. But wait, lets get nerdy
Clinton&Faye where they appear almost identical in height to Clinton maybe just a bit shorter, whether you look at eye line, chin line, or nose line, and now today
Clinton&Yay It looks like Yay is just a bit taller but otherwise directly looking Clinton in the eyes. Plus in yesterdays comic, Yay's hairline comes up to Elliot's collar bone, and in #3392 as noted above, Yay's hairline came up to a then armored Bubble's collar line but we have a direct comparison with
Bubbles&Elliot with both of their collar lines thankfully framed together to show that without her armor, Bubbles is still a number of cm. taller than Elliot which proves that I'm a ridiculous nerd.
At least thats why I think Yay is getting shorter, that is to say, I think Yay is specifically modifying a number of their body forms to appear less spooky to the crew, while also trying to becoming less smug, more personable, helpful, and understanding social cues.
As for round vs. square speechybubs, that may be a choice to sound more robotic like the other AI's in the cast, or could just be this particular body's cycle through the charging pod. I don't think its a mistake to cycle between square and round speechybubs, neck seams and no neck seams, taller or shorter, as last week Jeph went back and corrected Roko's long hair to short, and has gone and made post edits before, so I think its deliberate to illustrate how many bodies Yay has at their disposal.
Sorry for the wall of text, been noodling too long on Yay and May.