It is, but it has been reworked. Instead of not being able to use your action to cast a spell other than a cantrip if you cast a spell as a bonus action, action type no longer has anything to do with it. The rule is simply that you can only cast one spell using a spell slot per turn. This is much simpler, but it does mean that by RAW monsters can cast a non-cantrip spell with their action and their bonus action since they don’t actually use spell slots, and PCs who have features that allows them to cast a spell without expending a spell slot (like most species’ innate spells allow them to do), they can use such an ability in the same turn that they cast a bonus action spell.