You can see an anonymized 30-day bid history by opening the item listing page in a private or incognito browser window (or by signing out of your seller account), then going to the bid history page for the item and clicking on one of the now-anonymized bidder IDs.
Incidentally, this works for bidders who want to see their own 30-day bid history; when signed in, a bidder's own bidder ID is not anonymized, so clicking on your own username simply takes you to your profile page. To see your own 30-day bid history, you need to use the anonymized ID link. Once you have your own 30-day bid history displayed, if you sign in to your account in another tab and refresh the bid history page, the information is displayed with greater precision; for instance, the actual bid times are listed rather than rounded to the nearest hour.