Why is Direct Play working better?

When I try to play a high-resolution and high-bitrate video, that is in a .mkv container, I will often see it buffer a lot, to the point of not being able to watch it at all. If I enable FORCE DIRECT PLAY on the 2023 LG TV it is playing on (OLED65G3PUA), it plays without issues.

If it helps paint the picture better, the media server is on a Synology that has hardware acceleration capabilities.

Can someone explain why this would be working better?

TIA!