Some of the 32 bit apps have newer 64 bit counterparts but not through a normal update. They made it a new app to charge for a second time. You will see them as App xxxx 2.
I especially don't like the new versions that now have monthly subscriptions instead of a flat fee. You take an app that started out costing $1.99 or 2.99 and now they want $4.99 a month. It's a bit excessive to say the least. So far, every app that changed to subscription I deleted and went for something else.