I know from this question a critical hit on adamantine will still hit, but I was curious if the critical hit no longer being a critical hit affects features or feats that depend on it.
An example that came up recently in a kind of pvp session is I had adamantine plate armor, and my friend had Great Weapon Master. One of the effects of Great Weapon Master is:
On your turn, when you score a critical hit with a melee weapon or reduce a creature to 0 hit points with one, you can make one melee weapon attack as a bonus action.
Would a critical hit that became a normal hit still activate the bonus action melee weapon attack?