When using Minor Illusion (whether obtained as a cantrip from being High Elf or whether chosen at level 3), the description states that “You can remain hidden while casting this spell”. However, whenever the spell is cast while “Hiding”, upon completion of the spell you lose your stealth.
I noticed this too with Shadowheart casting it so it seems to be a general spell issue which I recommend being discussed in the more visible already pinned spell casting thread rather than a minor side thread.
It is also currently not possible to possess a familiar and have mage hand summoned at the same time.
We must be careful about this one. Mage Hand is already far stronger than intended in DnD5e rules such as being able to cause damage with an attack or counting as an enemy for the sake of sneak attacks in BG3. The fact that you cannot have a familiar at the same time counterbalances this a bit although I still feel Mage Hand to be overpowered being a cantrip. Mage Hand was supposed to be a help during non-combat related tasks like Minor Illusion. But Larian buffed it so much that it becomes a viable support during combat that can heavily impact combat especially considering shoving enemies from cliffs combined with the entire Advantage/Disadvantage stuff with High Ground/Low Ground which is also not part of the core DnD5e rules...