If you compare the first and last columns, it is clear that for some operators the average distance travelled has gone up.
GWR average journey about 15% longer, Northern about 8% longer, TPE about 7% longer. (The complete opposite of idea that people buy short tickets to get through barriers)
Taking biggest of these (GWR), they would have lost some Paddington local trains to Elizabeth line, so that suggests their 103.5% passenger km means they are almost certainly higher than pre Covid peak in other areas. I don't know exact proportion of their kilometres that got taken over by Elizabeth line, but must be 1-2%, so means running nearer 105% of pre covid
Sticking with GWR as an example, train km 103.7% is more than train km 97.6%, so on average they have cut train length by over 6%. As their fleet is virtually all fixed formation units, couldn't have taken coaches out, so must be running less units in multiple. And in practice that is what has happened, some 2x5 car IETs reduced to single units, 4&5car DMUs on services to Portsmouth reduced to single 3car units etc.
These days all operators publish performance figures, and these are GWRs latest
0.17% shortformed, so the 6.1% cut in train length is not short forming, it is is a timetabled cut of around 6% (even though passenger km is around 105% of pre covid). GWR cut the HST fleet (and a turbo, and some 387s), and gained not a lot (until they put 175s into service) in last 6 years.
What it does seem to flag up, is that although the statistics come out every 3 months, but reaction time to changing passenger numbers is an eternity in comparison. The industry doesn't seem to have the staff numbers or ability to hire in extra rolling stock at 3 months notice to react. It collects the data and isn able to react to them. Even looking at 6 year movement as we are doing now shows they haven't got anywhere near synchronising the train km to passenger flows.