eBay Adds Repeat Buyer Identification
UDPATE 5-27-22
Previously sellers had to click through to the actual order details page to see the repeat buyer designation, but not eBay has added it to the main Seller Hub Orders page view as well.

While it's definitely nice to see it in order list page as well now, I have to agree with this eBay community member who says it would be even better if that Repeat label could be a link to see past purchases from that user.
It would be great if you could click on the Repeat Buyer line & actually see what that buyer has purchased in the past.
As is, it serves no purpose for me. Nice to see, but nothing more.
UPDATE 1/4/22
eBay community staff have given some updated information about where the repeat buyer label will be seen within Seller Hub.
Here's what I've been able to find on it - details are a bit sparse at the moment:
The 'Repeat' logo will show beside a repeat Buyer's name in:
- Purchase details in Seller Hub Orders (If Buyer has purchased from that seller twice or more).
- Send Coupon from Seller Hub Orders (If Buyer has purchased twice or more).
- Best Offer/Received offers page (If Buyer has purchased once or more).
eBay is updating Seller Hub to give sellers more information about repeat buyers.
In the Performance tab, eBay says they are now measuring repeat buyers in a new way.
You may have noticed that your repeat buyer metrics have recently dipped or spiked. Repeat buyers have been redefined as customers who have made no fewer than two purchases in a two-year period.

However, there seems to be some discrepancy between the Buyer Insights section and the category breakdown below it. In this example, insights shows 2 repeat buyers, but the categories show 0 both in the visual breakdown and the available downloadable CSV report.


Sellers are also reporting eBay is showing a repeat buyer tag in order details, though this may be a phased rollout that is not available to all sellers just yet.

Hopefully this means eBay will soon be delivering on the promise of sending coded coupons to buyer groups, including repeat buyers. That was supposed to be released in October as part of the Fall Seller update but was "pushed back" with no updated timeline provided.
Sending coded coupons to buyer groups is an easy way for you to encourage existing and potential customers to purchase your items. For example, use coded coupons to target specific buyer groups when your seasonal inventory has the greatest potential to sell.
The following coded coupons options will be available starting in October.
Launching in October:
Send a coded coupon to your previous buyers to encourage repeat business

Have you seen repeat buyer identifiers in Seller Hub? Let me know in the comments below!

Example:
Buyer A made 2 separate purchases about an hour apart. Those are the only 2 purchases they've ever made from my store. There is no repeat buyer designation on the order details pages.
Buyer B made 2 separate purchases about 10 min apart. Those are the only 2 purchases they've ever made from my store. There IS a repeat buyer designation on the order details pages.
Both buyers appear to meet the same criteria, but one is showing a repeat tag and the other isn't.
For what it's worth, I don't think either example should show the repeat tag. I fully agree with FidoMaster's statement below:
"Grouping buyer purchases in a single calendar day seems the most sensible way to go (for the overwhelming majority of use cases)"
Results wouldn't be perfect, especially if eBay uses Pacific Time to determine calendar day, but it would be a lot more accurate than what we're seeing now.

I was thinking about this part you wrote:
"However, there seems to be some discrepancy between the Buyer Insights section and the category breakdown below it. In this example, insights shows 2 repeat buyers, but the categories show 0 both in the visual breakdown and the available downloadable CSV report."
And I was thinking about one of eBay's published details on what counts as a repeat buyer:
"If a buyer bought 2 items in a single order from you, that is also considered a repeat buyer."
Then I was looking at the repeat buyer banner on the Order Details page in Seller Hub.
I noticed that buyers that purchased multiple items in a single order did NOT get the repeat buyer banner in Seller Hub.
It appears there's a disconnect somewhere as to what eBay is counting as a repeat buyer and where they are counting it.
Could the 2 repeat buyers from the screenshot be buyers that purchased multiple items in a single order, but then in the reports it's not showing because eBay is either inconsistent or changing what designates a repeat buyer?
We know that eBay internal communication is lacking at times and this could be an example of one department defining things one way while another is defining it another way.
I don't know, but that's my current working theory.

They did not have any orders within that time showing the Repeat Buyer tag in order details.
They did have two instances of a buyer purchasing an item, almost immediately requesting a cancellation, then reordering.
My guess in the situation I used above as an example - eBay removes the canceled order and does not apply the repeat buyer tag in the order details and in the Sales By Category chart and CSV report, but is still counting those two as repeat buyers for the Buyer Insight section.
Talk about unnecessarily overcomplicated misexecution if so. 🤦♀️

The Buyer Insight section is way too generous in what it counts as a repeat buyer, but the fact that it's not matching up to all other areas labeling repeat buyers is adding unnecessary confusion. The parameters should be more clearly defined and applied to all areas consistently.