Monn Millenium leaves yellowing while blooming?

[Mollyobolensky]

I’ve had my millennium magic orchid for about 10 months and am a beginner orchid caretaker. Unfortunately this orchid suffered dehydration (due to me being unsure of when I could water and how much to water again) but other than that seemed happy.
About 9 days ago, my first flower spike started developing and seems to be growing happily.
However on the psuedbulb that isn’t flowing, the leaves are turning yellow and dropping.
What am I doing wrong? How can I save my orchid? (((