The placebo here was saline (no physiological effect). Sometimes they give amphetamines as a placebo so the control group also feel that something is different. But I’d expect that to affect RL hyperparameters too.
Are you sure you have really taken 100ug? The blotters these days are very often quite a bit less, although marketed as 100ug.
100ug should be enough for most for a good trip.
This was my first thought. There’s no way that anybody would mistake 75 ug of LSD for placebo.