Sounds like a bit of an internet rumor tbh Paul. There have been reports of a few isolated failures on spoked rears, but there's nothing from Ducati about a "recall" to replace the rear bearings. If there's an issue, then it would be sorted via the warranty procedure with new parts. There have been no part number substitutions either, suggesting the bearings remain as original spec etc. Wheel bearings should always be checked when a tyre change is done Fraser.. the Pikes Peak isn't affected at all as it runs a single sided rear with a completely different set up.
Quick Update – Bike is a 2021 V4S now with 21K miles. Last time out it got very dirty and had a full clean (no jet wash) and then sat in the garage for 4 weeks (due to Xmas, New Year and Weather!) until last week. Noticed rear wheel was very stiff to rotate when rolled out of the garage but all well on a 120-mile ride, except that at 45mph + there was a noticeable droning noise that I thought was from the rear of the bike (I don’t carry a pillion). At the weekend I removed the rear wheel to check the wheel bearings, they were very dirty around the seals so cleaned it all up with the wheel removed. On further inspection the rear wheel bearings were lumpy to rotate and felt like there was grit in there. Took the wheel to my dealer (PT) and they confirmed the bearings were shot and were replaced there and then. Both the wheel and sprocket carrier bearing (2 on the wheel and 2 on the carrier) were replaced. The old (that is the original OEM) “sealed” bearings had brown seals and were stamped "China" on them, one on the brake side of the wheel was corroded in and hard to remove. The replacement bearings have black seals and are stamped NRG. I am told that rear seals should last about 20k miles on the twin spar rears as they are smaller whilst the SSSA bearings are bigger and better! Wheel refitted today and it felt smooth and easy to rotate, very easy to wheel out of the garage. On the road it is definitely quieter, still some speed related noise from the rear of the bike but I reckon that is just chain noise. Bottom Line - At 20K miles it would be good idea to check those rear wheel bearings. I don’t think that a rear wheel bearing check is in any service schedule that I know about.
When I stripped my spare wheels in prep for powder coating I found the same, my spares only had about 3.5kmiles on the bearings. I think the external oil seals had been put in dry & the seal springs had rotted when water got in , this held the rusty paste created against the bearing seals & the resulting rotations got this past the bearings seals making the inners in toast. I made sure the new external oil seals were loaded with grease when fitting in to the spares and my other set to try to avoid a repeat (hopefully).