This is like a trial run for Rashford at Barcelona. If Rashford performs well and contributes significantly to the team, Barcelona will certainly sign him, regardless of his price tag and salary. Now, Barcelona wants to try him out first, and I think this move benefits everyone.
In terms of individual quality, Rashford isn't bad, but he hasn't developed at Manchester United. Playing for Barcelona next season remains a big question mark, although it won't be easy for Rashford, as he faces a lot of competition for a starting spot.
Rashford is the heat of attraction because for Barcelona to be buying him shows that the moment he does not do well, then they are going to gaslight him because he is getting the whole hype because they feel he might do very well in Barcelona, that might be the peak of his career, and people especially are serious about Rashford doing very well. And the price is not bad for a class player, so the only thing is that Rashford should give Barcelona exactly what they want, because one of the reasons they bought him is that they need to improve his performance.
And maybe the performance of Manchester United is what is making everything look like Rashford is not good, so there is a good chance that Barcelona might be the best option for Rashford, because Manchester United has not been doing well, so that might be hiding a lot of talent.