You're right, the original elset for the Turksat 4A tank was for a higher orbit, but then it was altered to one similar to the Turksat 4B early elsets.
In general, at least for commercial Proton-M/Briz-M launches, the more massive the PL is at separation, the lower the orbit the APT is jettisoned into, because the Briz-M uses its fuel faster, the APT is depleted sooner, and tossed off earlier. Turksat-4B is supposed to have slightly more mass than Turksat-4A (4,924 kg v 4,850 kg), and it has an apogee height that is ~570 km lower. For extremely 'light' payloads, the 3rd and 4th Briz-M burns are combined into a single burn, and the APT has an apogee height at GEO altitude.