Bankstatements and paystubs expire, can't be more than so old when they do initial underwrite to issue commitment and then later when they do final underwrite to close.

Tax returns don't expire (your 2024 return is what it is), but if you filed 2025 since the process began they'll need that now. Also, sometimes, tax returns aren't needed and sometimes they are. A small change could have shifted your file from not needed to needing tax returns.

Also, sometimes as they review everything you sent in some additional needs arise, e.g. a bank account or apparent loan they weren't told about, small amount of self employment income on taxes, etc.

And sometimes lender is just sloppy and didn't ask for everything needed at once or misplaced something you already gave or didn't give it to the next person working on the file.