LDAC has its flaws – **** battery life, a lot of unnecessary stuff and poor range – often times pretty bad. Snazzy Labs has a video on it in his review of the APM
I've done my own testing and with the same song on the same headphones (Sony WH-1000XM3, which supports LDAC) and an Sony Walkman with BT and LDAC and compared to the iPhone (AAC). Using the headphones wired on high res audio sounds exactly the same as wireless over BT with LDAC, on the iPhone (AAC) sounded noticeably worse. And with a high-end audio player on iPhone and wired over lightning did sound a little bit better than Bluetooth (AAC).