At my last job, my work was basically to read data from proprietary APIs and shit an excel table.
I think I was hit by everything. Easy stuff at first: Crlf issues, XML Apis, weird rpc apis.
Then, halfway through the project, the results had to change. Not only the order, datatype and headers (I actually overengineered the first version so those were configurable), but the format, duplicate on multiple columns (and empty fields counted as duplicate...). Worst job I've ever done. I'm also disappointed in myself tbh.
But now I'm a bit of an expert on excel format issue and limitations, and that already helped me.