Jadon Sancho is a player that understand Borrussia Dortmund, all he needs is to be fit and move according to the plans of the management and the coach. I don't doubt his capacity for that club, so much comes with playing for Manchester United, you either adapt or run away, and no player stands a chance above the manager, him leaving not good but Manchester United have to sacrifice for the long run.
I'm not sure if Jadon Sancho would work out at Dortmund again. When he left the club it was a different team, with Haaland, Bellingham, Gureiro, Hakimi and many more. With all the players he played so well with and could perform with and reach the high market value are gone. Dortmund haven't bought new players well in recent years and that's why they have problems. If Sancho was in top form, then maybe he could improve the team. But an out-of-form player in an out-of-form team will not work.
Sancho departure was the end of the dispute within Man United, in Ten Hag mind Sancho was a disease within the team. Now that all disputes have been temporarily resolved, Ten Hag can manage the dressing room without any more disturbances from his players. For Sancho, this is a second chance to rebuild his sinking career, Dortmund as his old home will be the right place to show again that Ten Hag was wrong to ignore him at Old Trafford. However, it does not rule out the possibility that Sancho will repeat the same behavior, but the hope is that Sancho will show his gratitude to Dortmund.
If we quote transfer expert Fabrizio Romano, Dortmund has no obligation to buy Sancho permanently after the season is over, that's why Sancho must be able to convince all parties that he can be useful for the team he plays for. I think Sancho can be useful for Edin Terzic, to help his squad penetrate the top four of the Bundesliga standings, as well as help Dortmund to be able to talk a lot in the Champions League. As a former Dortmund player, I think Sancho will have no difficulty adapting again.
Previously, Juventus was reportedly interested in loaning Sancho, but currently this has not materialized, the player prefers to return to his old club. It could be that Juventus cannot afford the amount of salary that Sancho wants, but despite this, Sancho is now a new Dortmund player, at least for the next six months.