Extracted folders have the created/modified date set to the time/date of extraction
This is a known feature request (#1174), Status: open.
See also this 7-Zip discussion thread ZIP archive folder date preservation.
#1174 Preserve original file creating\edit dates when extracting
Now when files are extracted their creating date, edited date are set to current time despite in archive they could have their own dates, an option to preserve those would be very nice.
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The hard part is already done. If you just right-click and under 7-zip, extract here/to, it should perform as expected.
After testing it appears that the above comment is incorrect and doesn't work.
Source #1174 Preserve original file creating\edit dates when extracting