It looks like he doesn't have as much Power as before, he's weakened, probably the stress ate him up after the heavy criticism, and his mental state also affected his physical state...
Think he's just afraid to bite down on his punches, Mostly throwing to score points nowadays rather than to put hurt on his opponent. Still didn't look as bad in this regard as he did in the first Usyk match though
Joshua is a decent puncher and carries good power, but he never really was a one punch KO artist. What surprises me more, is the fact that he is so weak in the clinch. A small man like Franklin threw him away like it was nothing. Joshua is a massive guy and build like a tank, but Fury is so much stronger.
I don't think he has lost strength, he's just not fighting like a boss anymore. He isn't getting the torque on his shots (look at the hooks he missed against Ruiz right before the first KD) as he's now thinking more about the incoming. Watch how he shifts his weight forward when he throws this right hand trying to finish off Ruiz in their first fight. Followed by some dangerous whipping hooks. Different story now. This content is protected
As said above, he's just not committing to his punches anymore and it seems to be getting worse. Pre-Wlad Joshua would have stopped Franklin and pretty quickly too because he wouldn't have wasted a single thought on what was coming back. And contrary to popular opinion, he's not a massive puncher. Don't get me wrong he hits HARD, but there was always the element of the accumulation of punches which set up his stoppages, and he doesn't throw combinations like he used to either. Wlad may have lost when they fought, but Joshua lost something getting the win - that unwavering self-belief he would get to his opponent before they got to him. Only in Ruiz 1 did he revert to the wrecking ball approach in round three - and look how that worked out for him. So the issue which emerged vs Klitschko was compounded. The power is still there but he's stopped using it, preferring to fall back on his jab - the one punch he throws better now than he did back in his prime...
He lost his confidence and aura, it's made him gun-shy and more risk averse. The Ruiz fight did it, I don't blame him either, must have taken a fair amount of mental endurance to recover from a loss like that. His style is still effective against decent B fighters, I think he beats most top 10s, just comes unstuck Vs Fury, Joyce and probably Wilder.