RS7 High RPM Acceleration Issue

[Imss1106]

Hi guys, have a 65 reg RS7 (bone stock) non-performance pack which has had its oil strainer recall work carried out.

As I went for a spirited drive earlier I noticed that as the vehicle got to around 5,500 RPM+ the pace in which the vehicle was accelerating at dropped dramatically.
It was almost as if the vehicle was hesitant to accelerate and took a few seconds to shift up to third-gear.

Definitely wasn't a gearbox issue.

I've never experienced anything like it before, the vehicle gets serviced every 2,500 to 3,000 at the main dealer and have not had any fault codes come up.

Has anyone else experienced anything like this, and any idea whether its something potentially serious?

Any feedback would be greatly appreciated!

Cheers.