The yield on GLP Vault dropped on GMX due to market conditions. The yield is determined by the demand and supply of the asset, and when the demand decreases, the yield also decreases. This can be caused by a variety of factors, such as a decrease in the asset’s perceived value, a decrease in the amount of liquidity in the market, or an increase in competition from other similar assets. In any case, the decrease in yield on GLP Vault on GMX is likely due to a combination of these factors.