Placing an ender crystal on a block of bedrock or obsidian and destroying it causes nearby entities to be damaged, however there are no explosion particles. If an ender crystal is placed on a block of bedrock or obsidian, the block below it is removed and the crystal destroyed, it damages nearby entities but does not damage the map and create particles.

I confirmed that this is not a client side bug by attempting this same procedure on a 1.17 client connected to a 1.16 spigot server with via version.