Gah, thank you. The drop down is one of those terrible ones with no scroll bar and only three entries so I have to do the ol 'scroll wheel and hope' to discover more options.
Only on TGZ files, not zip, which maxes out at 4GB. (This is not because of a file size limitation. The only way to get 4GB is through zip64, which has a file size limit measured in exabytes.)
For you and me, not a problem. My wife is a medical professional and would have no clue what to do with a TGZ file.
Also, the fact that they don't mention this difference- the UI is so poorly done that you can only tell that TGZ can go an order of magnitude larger after selecting it in one drop-down and then looking at the other drop down- is a sign of how Google wants to make this as difficult as possible.