According to James Horncastle from The Athletic, Rabiot's salary is €7M net, and in Italy, only 50% of the salary earned by foreign players is taxed, the other 50% is exempt, and the top tax rate in Italy is 43%, which means it is effectively 21.5% tax rate on the full salary.
So, Rabiot earns €7M net, which is €8.5M gross, and if it is to be matched in England, and accounting for the tax paid by PL Players, then his salary is £210K now, which is in line with other top earners like Sancho, Rashford and Bruno.
I saw some posters say that he earns 500K a week at Juve or some other ridiculous numbers, which are totally untrue.