The Greek war hardened the Pasha's resolve to rebel. [causal]
What finally tipped the balance towards rebellion was the Greek war which the Sultan had asked him to intervene in, thinking that it would weaken his strong vassal. Instead, the Pasha used it as an opportunity to try out his new troops and by the end of it he came out more resolved than ever before not to co-operate with the Sultan in the future. As far as can be discerned from his own letters it does not appear that he had contemplated military action against the Sultan before that time.
Builds on: "The Greek campaign permanently poisoned future Ottoman-Egyptian military cooperation."
Khaled Fahmy, All the Pasha_s Men_ Mehmed…, loc. 265