I will just quote a post from Secretprojectsforum (https://www.secretprojects.co.uk/threads/turkish-tfx-national-combat-aircraft.13448/)
By "PringleiPrick"
"W.r.t. to calling the TF-X a stealthy F-15EX is selling it a bit short, in my opinion. I think you're right in terms of flight dynamics...
One thing, i have seen nearly all media outlets using "Iron Bird" but this is not Iron Bird testing, this is static stress testing for Hürjet, Iron Birds don't look like these
No, I remember TEİ stating the tests (flying) will start in 2028, not serial production.
Given that they test the engine for around 4 years (2032), we would need ~200 engines for the production.
This deal is probably for that