So GV is just mere fraction of Harald/Loki flashback lol.
Maybe the hype back in chap 957 was too much that we expect a little too much.
Oda excels at creating hype around by teasing it.
At the end it's not even a major events that Oda likes to separate specifically and write a detailed events about.
Xebec too, from being speculated to be a secret final boss by many and still alive somewhere to play bigger role........turns out he's just merely for a Teach upscale and secondary character of someone else flashback.
Most of his actions and W are offscreen too.
Muweh.