When really put the pedal to the floor, I go into limp mode (usually when lifting off the accelerator, or gear changes up) code is Turbo Overboost. Learned to live with it, she's hardly a sports car anyway.... but still. It'd be nice to say "Yes.... i can overtake this car" without worrying about it.

So my question is... carbon gunk and sticky vanes, or a dodgy actuator?

Ran the airpath test on SDD, and got this. To me that looks like the vanes are jammed in the high rev position - would make sense when overboost error kicks in when taking foot off the gas. ERG is blanked. Visual under the car sees the actuator arm moving while revving the engine.

Click image to enlarge

Click image to enlarge

It’s easy enough to disconnect the actuator arm (don’t lose the clip), & see what the turbo link feels like. Give it a lube & try again. (Now Sold). 2008 Freelander 2 (Nazca Sand) SE TD4 Auto. Statutory write off & on WOVR for hail damage but still road legal.
171037Km as of 09/05/22
Superchips Bluefin Flash
Nanocom Evo II (also sold)

In my experience, if the EGR is blanked, it will upset an air path test or calibration. Remove the EGR blank and run the test again. 2009 Rimini Red SE TD4. Soon to be sold.
Hyundai Ioniq 5 Ultimate on order.
Gone. 2006 Tonga Green i6 HSE.

More likely to be carbon build up on the variable geometry ring.
I didn't drive mine hard and that's exactly what happened to mine.
Driving like miss Daisy doesn't work the mechanism hard enough to keep it clean. Now at the point when I learn something new something old is lost out the other side !
Now retired so it doesn't matter anymore.
Freelander now gone.

The dealer ran some sort of 'exercise' procedure, I haven't had a reoccurrence of the Restricted Performance (Turbo) since, --- see link

https://www.freel2.com/forum/topic39340.html?highlight=turbo FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 76k+ miles) (MY2015)