With the exception of EK, TK is the only (nearly) middle east carrier that offers more than once daily world-wide connections via its hub. Its is of course competing with the likes of EK/QR/SV, but the later two dont have consistent connections daily across the week. Therefore for them to compete, they need keep this connectivity up...
Interestingly, looking at the Aug'23 figures:
BHX-IST (Aug'23): 17,455 Pax
BHX-IST (Aug'22): 19,069 Pax (-1,614 / -8%)
So quite the impact, but then in Aug 2022, Turkish wasn't competing with QR or SV. However, now the pressure is one. 2x daily with bigger aircraft is one way it can complete, be interesting to see if they upgrade further to wide-bodies in summer next year or decide to introduce 3x daily flights on some days....