OPEC's market share is essential unchanged over the decades, 40%, except during past times where they significantly reduced production to raise prices, then it recovered back to 40%.
This isn't the first time they have had major disagreements.
Yes, they have always adjusted their production to keep their market share at 40% of world demand. Now, the cartel seems to be loosing its control of production levels. Too many of them need to keep pumping to support their debts/outgoing cash flow.