In this question on the Puzzling Stack Exchange, I wrote this answer with some Mathjax, but it formatted a little weirdly. Here is what I wrote:
Some unecessary information, blah blah blah
The following is another one less technical.
$$\underbrace{(2+0!)}_{3}\|\underbrace{(1+\sqrt{9})}_{4}=34\tag{$\|=\small\rm concatenation$}$$
Notice that the right underbrace is significantly larger than the left one. I presume the square root and the brackets are to explain why this is the case.
Is this a bug? If so, should the large underbrace be fixed for smaller size?
Here are some other examples:
$$\underbrace{1+1}_{2}\quad\underbrace{\sqrt{1}+1}_{2}\quad\underbrace{1+\sqrt{1}}_{2}\quad\underbrace{\sqrt{1}+\sqrt{1}}_{2}$$ $$\underbrace{(1+1)}_{2}\quad\underbrace{(\sqrt{1}+1)}_{2}\quad\underbrace{(1+\sqrt{1})}_{2}\quad\underbrace{(\sqrt{1}+\sqrt{1})}_{2}$$
The same applies to overbraces.
$$\overbrace{1+1}^{2}\quad\overbrace{\sqrt{1}+1}^{2}\quad\overbrace{1+\sqrt{1}}^{2}\quad\overbrace{\sqrt{1}+\sqrt{1}}^{2}$$ $$\overbrace{(1+1)}^{2}\quad\overbrace{(\sqrt{1}+1)}^{2}\quad\overbrace{(1+\sqrt{1})}^{2}\quad\overbrace{(\sqrt{1}+\sqrt{1})}^{2}$$
Original screenshot:
The expressions are nearly all the same size, differing just slightly. But the braces (over and under) differ significantly. Apologies if the screenshot is blurry.
New & Improved Screenshot:
Thanks heaps to @Martin Sleziak for this, particularly this Meta answer!!