I wonder if some noticed there is one rule that both BG3 and Solasta changed and I have seen NO ONE complain about it !
In both games, you can cast an Action spell and a Bonus Action spell in the same turn (ie. I do NOT mean a cantrip, but rather you can use two spell slots/turn in both games).
In vanilla 5e, you can use one single spell slot (spell level 1+) along with one single cantrip in one turn. Meaning you cannot use a spell slot for an Action and then another spell slot for a Bonus Action in a single turn. Example : In one turn, you could cast Firebolt *cantrip* (Action) and Healing Word (Bonus Action).[note 1]
The rule is not bypassed by having an extra Action (the limit is per turn. If you get an extra turn with some powerful magic, then sure, you can cast more spells). (EDIT: turns out WotC meant per Action and not per Turn, sigh. Bonus Actions are restricted to 1 only per turn, hence the confusion. So you can do Action Surge to cast two spells of levels 1+ along with one single Bonus Action spell!)
Anyhow, this flexibility in BG3/Solasta seems to please most people as no one ever mentions that homebrew !