I'm not sure FFP is having a negative impact on Arsenal - we just have a policy of trying to find value in the transfer market - basically we're a bit tight. The odd crap signing like Nicolas Pepe excepted. If anything FFP has helped us else the likes of Newcastle, Chelsea, City etc could price us out of the market massively.
A few of our signings/academy players would sell for massive fees - you'd have to think the likes of Saka and Saliba would be up and around the £100m+ price range, Odegaard maybe a bit less and if we had to cut our losses on Declan Rice I'm sure there would be takers at around £90m+. In a couple of years any transfer fee for Ethan Nwaneri could be astronomical, depending on if he realises his full potential. We'd also make a healthy profit on Jurrien Timber, Gabriel and David Raya. Kai Havertz less so. So on that basis we are pretty sound. Also getting £34m and £30m for Emile Smith Rowe and Eddie Nketieh respectively was great business.
United in the other hand have seen FFP rules bend them over a table and go in dry and that's because they spent so much money on garbage that they can't recoup in transfer sales. Such a pity.