Microsoft is a substantial shareholder (49%) in that for-profit subsidiary, so the value of Microsoft's asset has presumably reduced due to OpenAI's board decisions.
OpenAI's board decisions which resulted in these events appear to have been improperly conducted: Two of the board's members weren't aware of its deliberations, or the outcome until the last minute, notably the chair of the board. A board's decisions have legal weight because they are collective. It's allowed to patch them up after if the board agrees, for people to take breaks, etc. But if some directors intentionally excluded other directors from such a major decision (and formal deliberations), affecting the value and future of the company, that leaves the board's decision open to legal challenges.
Hypothetically Microsoft could sue and offer to settle. Then OpenAI might not have enough funds if it would lose, so might have sell shares in the for-profit subsidiary, or transfer them. Microsoft only needs about 2% more to become majority shareholder of the for-profit subsidiary, which runs ChatGPT sevices.