“This is a String” is yielding ThisisaString when executed in Mathematica Online.
I first noticed this today when previously working PlotLabels in BarCharts had their spaces stripped. Doing a little checking, the problem seems to extend all the down to strings themselves.
I’d guess that code updates are pushed on a pretty regular basis and that this is a bug that got introduced and snuck by SQA. Let’s see when the fix gets pushed!