I would not call that a U-turn:

Instead, the government pledges to meet the 2 percent target on average over a five-year period, as already set out in the recently published National Security Strategy.

Seems more like the same direction, just on a parallel lane.

On the one hand debatable, as it doesn't come 100% in line with the wording of the NATO guideline. On the other hand a practical course to measure across 5 years, as in some years there are larger procurements required than in others and overall the 2% are still met.