Income and spending rose less than prices in May.

The group, known as OPEC Plus, is at what could be an important crossroads. It has largely completed — at least on paper — its program to reverse the deep cuts in oil output that were put in place in the pandemic, bringing the total production target to about 44 million barrels a day, roughly the prepandemic level.

Among the issues facing OPEC Plus: the fact that its output quotas for different member countries are overambitious, leaving…