Plenty of spells cast as a bonus action. With a cleric I can cast Spirt Guardians and Spiritual Weapon on the same turn. Or polymorph and mass cure wounds. It makes a significant difference for bonus action spells.
The most significant change I noticed was you can cast any number of leveled spells per turn. That’s a pretty significant shift from 5e’s rule of only one leveled spell (excluding using action surge if you dip into fighter) per turn.
However it makes the player stronger so I doubt anyone is really complaining about it.
Does breaking your oath make you an Oathbreaker in BG3? Because that’s not how Oathbreaker works in 5e.
A Paladin who forsakes their oath would just be a fighter. Oathbreakers are specifically Paladins who call upon the forces of evil for their strength rather than the divine. They don’t just break their oath, but twist and pervert it for some dark power.
One of the biggest changes is ranges of attacks. An Eldritch Blast has a range of 120ft in 5e. In BG3 all ranged attacks have been significantly shortened (less than half for Eldritch Blast) so they can’t be targeted “off screen”.
As a design philosophy, Larian dislikes people being hit by attacks from off screen so they limited the length of ranged attacks.