Since the introduction of the 'new' Ticketer machines it has been possible to collect vast amounts of data that can then be used to model passenger journeys & flows, so it is no surprise at all to see routes such as the 48 & 87 cut, again the same data would have been used to decide the operating days/hours of the park and ride sites - for instance, when the Stourton site (PR3) opened passenger numbers at Temple Green (PR2) reduced. Elland Road although generally well used has the additional hindrance of not being available or reduced hours on match days. Withdrawal and recasting of services will also allow some of the loan drivers (from Doncaster, Leicester etc) to return to their own areas'.
Personally, I think that the Leeds Park & Ride services should interwork with each other, so PR1 becomes a PR2 in the city centre before returning to run a PR3 which in turn returns to run a PR1. It would mean fewer staff changeovers and a bit of variety for the drivers. It would also mean a common livery rather than the current colour coded fleet which reduces flexibility, although I have seen a PR2 branded Streetdeck run a 34 to Otley before now. Then on Sundays simply run the Temple Green site as a sole service between 0900 and 1800.
With working from home becoming more common and the rise of internet shopping it is highly unlikely that passenger numbers will ever get back to pre covid levels - and as soon as the government £2 flat fare finishes more and more routes / services will either be withdrawn or recast. The £2 flat fare whilst the intention was good it hasn't really attracted 'new to bus' usage most are twirlies taking advantage of a cheap outbound journey pre 09:30 and use their card to return and to be fair £2 single Leeds to the coast who can blame them?
it is rumoured once the £2 flat fare finishes that in West Yorks there are a minimum of 50 routes (across all operators) under threat and many others that will operate 07:00 to 19:00 Monday - Saturday & little or nothing on sundays.
If we look at the 50 odd routes, specifically the First operated ones I can see that there would be quite a few in Calderdale being cut completely on Sundays - namely the 548 which runs only between Brighouse and Nunnery Lane on Sundays and that carries insufficient numbers, the 549 between Brighouse and Halifax which carries around a third of a bus full (varies each week when I've seen it, sometimes its been empty). This could be solved by simply withdrawing the 549 and instead extend the 586 (Halifax to Commons) through to Brighouse via the 548 route which would becomes a Brighouse to Commons service.
Then there's the Halifax to Rochdale/Burnley via the Calder Valley services 590/591/592 alongside the 579 to Sowerby, which I can imagine seeing the Sunday journeys on the four routes being withdrawn and being palmed off onto a new "593" and routing it via Sowerby Bridge as a partial replacement. The Sowerby to Sowerby Bridge section is covered by a heavily revised 577 by Transdev (read as every two hours, last bus at 6pm) and at the Todmorden end the replacement "593" would alternate between Rochdale one hour and Burnley the next. The 510/511/512/513 to Mixenden and the 521/522/523 to Illingworth could somehow be merged into a Sunday & public holiday only "North Halifax circular" by taking in bits of the 510/512 or whatever the route is up through Pellon and Mount Tabor and bolting that onto to the 522 to try and avoid cutting off the villages completely, this could run hourly but in alternate directions.
Maybe having a "Halifax Sunday network" whereby running simply five routes may be the best way to at least provide some sort of Sunday service, even if its every two hours. Where as in Huddersfield it would somewhat be one route serving the Colne Valley (read as 184 to Oldham), one route for the Holme Valley (more likely merging the 310 Hepworth and 314 Holme to become a "315" Huddersfield to Holme via Hepworth), the 503 to Halifax, the 363 to Bradford and the Uni bus to Storthes Hall - with the rest losing their Sunday service. In Leeds, it would be a lot more complex but I could imagine seeing the 64 to Aberford being withdrawn altogether.