Companion and mount upgrade are not the same as equipment/weapon upgrade. During equipment/weapon upgrade, you can examine their current attributes and their upgrade attributes. Companion and mount upgrade do not have that. We don't know what it will be upgraded to. We just guess and assume. Often, we assume wrong. Mount upgrade is worse than companion upgrade because we cannot even see the current attributes of the mount in the stable. The UI can be changed to like the equipment/upgrade with the token as regent and 100% chance and no RP. Top icon (current) has tooltip. Bottom icon (upgraded) has tooltip.
*** The game can read your mind. If you want it, you won't get it. If you don't expect to get it, you will. ***