I think opposition teams have sussed him out and know how to defend against him.
It's not rocket science tbh, if you stick a player like him out on the RW, his only choices are to either beat the defender for speed, but that would require us to release the ball early to him to give him space to run onto, but if defenders sit a little bit deeper, you limit his space, so he has to rely more on his explosive turn of pace and his dribbling skills to beat them, but both of them have dropped a notch since Afcon. His other option is to cut into the centre, and unleash that lethal left foot of his, but how many times have you seen Mo done this last season ? I can only think of a few. Defenders know when he cuts in, he'll try to shoot on his left, and it's not difficult to anticipate and defend against that.
So his only other option left, if all of the above fail, is to try to chip/cross the ball when he cuts into the middle, or play the overlapping fullback or whoever, on his right, onside. Which is probably why you're seeing Mo being more of a provider in the last few games. It could also be down to a change of tactics to accommodate Nunez or it could also be because Mo realizes his territory on the flanks, which he has dominated for years, is getting more congested and tighter, and he's being told to switch things up, instead of trying to beat his man every single time.
I can think of a few tactical changes to create more space for Mo to run and hopefully get back to his scoring best, but that would also mean focusing the team's play on one player, and i dont think Klopp and co wants that long-term. One thing noticeable is that Mo plays better when Mane was around, because Mane's runs on the left, creates space for Mo too, especially when we counter attack with speed. Defenders are forced to spread wide to cover both flanks. We're hoping Diaz will do the same too, but he doesn't really run the same lines like Mane (yet) and you can see he's clearly being told to occupy the same sections of the pitch like Mane, so maybe he's still learning but i've yet to see the same wavelength and partnership that Mo and Mane once had.
Another thing i can think of, is to get a midfielder - not just any midfielder, but someone who can dribble, and buy you that extra 1-2 secs, one who can dictate the tempo of the game comfortably. Someone like a Viera. Players like these open up spaces all over the pitch, which Mo thrives on. That's probably why i think Klopp finds Jude a very attractive option because he fits that mold.