The answer to the billing question has revealed itself - it looks like the fees are billed per listing at the end of the day following the click and netted from MP balance.
All of these clicks happened throughout the day at various times on 9/17 and they all hit the account right around 11:15 PM Pacific Time on 9/18.
When I didn't see them coming out immediately like PLS, I had hoped maybe that would mean they would aggregate and be deducted as a lump sum on a set schedule (daily, weekly, or monthly).
I suspected once a month was probably a far fetched idea because eBay had done so much previously to change everything from monthly billing to upfront with other fees, so I couldn't imagine they'd want to wait a month to get paid for these fees too - but I also thought if they did each click individually that could get very messy on the MP reports, especially for large retailers that are most likely to use this type of advertising.
They are grouping all clicks for a listing together, so that is less line items than each individual click, but I can still see it being a little messy if you opt thousands of listings into this and have the budget to get clicks on them all daily.
If that would be a concern, my suggestion would be to use PLA more like a scalpel than a sword - carefully select only a handful of listings most likely to benefit from these types of ads and really focus on optimizing the keywords to get the best conversion rate possible on clicks for those select listings rather than using the shotgun approach of blasting thousands of listings out there just to see what sticks.
Here's what the detail page looks like for both a listing with a single click and one with multiple clicks.
All of the detail pages say (America/Los_Angeles) which appears to just be showing that the date of 2021-09-17 is based on US Pacific time. I wanted to note that specifically just so there's no confusion or concern that all of the clicks may have come from the same location.
This is just what I've been able to glean from playing around with it - so as always take it with a grain of salt and other sellers may not see exactly the same thing I am. 😊
I'll also update here if I hear back from eBay with any more official information this week.
Also an interesting note to add - I noticed 2 clicks disappeared between when I ran the report earlier in the day on 9/18 and when I ran it again today.
Here's the first report:
and the second report
The click for $0.12 is gone and one listing that was showing 2 clicks for $0.25 total changed to 1 click for $0.09, meaning a click for $0.16 was also removed.
The adjustment to the clicks was made sometime after I had pulled that report which would have been around 11:30 AM Pacific and when eBay billed for those clicks around 11:15PM Pacific and I can confirm the amount billed did not include those removed clicks.
So this may be some good news for those who are concerned about click fraud? I can't say for sure that was why those clicks were removed, so it would still be nice to have some more clarity from eBay on this, but at least it does appear they are monitoring the clicks and have the ability to adjust them if there is a reason certain clicks shouldn't be counted.
