But imho in his 3rd year he was not supported enough if you aimed to fight for the title because your squad was nowhere near good as City's (and imho still not as good and/or balanced as other rivals).
This isn't an escuse for the terrible third year but yes, I do really thing he wasn't supported enough for the expectations you had.
Jose failed at United pretty spectacularly as well. This idea he wasn't backed properly in the 3rd year means the collapse was inevitable is nonsense.
Solskjaer didn't get Haaland, Bellingham, or Sanch, three priority targets he set because the club decided it wasn't prudent for a variety of reasons in each case. He didn't spend weeks moaning about transfers or denigrating the players at his squad. He's gotten on with it and after a weird start with little preseason there are positive signs he's turning things around.
Additionally he didn't inherit some buoyant 2nd place team with a bunch of rising talent on the cusp of stardom. He inherited a broken team in terms of spirit and style, a mishmash of a broken unfocused transfer policy of 3 previous managers well off CL qualification pace on the heels of being thoroughly embarrassed by City and Liverpool in the league. He was nearly able to get us into top-4 the first season but came up short.
Since then he's been focuses on turfing out high earning disappointments and players who simply didn't fit his vision like Lukaku, Alexis, Smalling, etc. He's had to work under far more financially stringent conditions and promoted youth internally.
Under him players who stagnated or regressed under Mourinho such as Rashford, Martial, Fred, Lindelof, Shaw, etc. have improved and we've seen youth players like Greenwood and Williams successfully be integrated into the first team. He was forced due to lack of options and a failure on the board to deliver an attacking mid to field Pereira and Lingard regularly. Once we got Fernandes our form immediately matched the best teams in the league.
No, he's not perfect. He's made mistakes numerous times, and if I'm being honest I'm still not sold he's the man to lead us back to the top. I wonder about his ability to coach attacking patterns to break down teams that sit deep, although I think his big match tactical ability should be beyond question at this stage. However, what he has done is an excellent job of restoring a sense of actual togetherness at the club and a commitment to building the squad with a focus on your, creativity, speed, and character without ever throwing players or the board or anybody else under the bus unlike his predecessor.
Mourinho is one of the greatest managers at all time but it sure as hell isn't because of a single thing he achieved at United. Solskjaer is unlikely to ever be viewed as such but what he's done at United deserves far more credit than he gets and certainly more than Jose ever should.