I can teach a wizard any spell from any class spell list.
In regular DnD 5e, wizards can only scribe wizard spells into their spell book. With this change, I feel like other casters (warlocks etc) don’t have anything making them as enticing as a wizard! Why be a warlock or a cleric with a limited spell list if I can just be a wizard and cast literally whatever I want? The versatility is through the roof compared to the already-versatile wizard of regular 5e.
It's a bug confirmed as a known issue to be fixed.
I logged a bug report and was given this response.
