The latest ORR report shows GWR back to 96% of pre pandemic services (table 4.1), but are only operating 93% of vehicle Km (table 5.1). Thus on average trains are shorter.
Meanwhile average GWR passenger is travelling 15% further (table 2.2)
ORR doesn't split by Operator the breakdown by commuter, long distance and regional split. However been suggested (in other threads) that for GWR commuter is down about third, long distance similar, and regional nearer 115% of 2019 figures. So obviously the squeeze on train lengths is tightest on the long secondary routes
So DfT meddling has done nothing apart from cut 7% of vehicle Km operated, but generally in wrong place by stopping turbos moving west, and attacking the castle HSTs on long secondary lines, both of which affect the areas that are booming.