Hot flashes worsening again after years of being tolerable

Hello,
My father has received monthly Lupron injections for ten years and after the initial few years, the hot flashes became tolerable and extremely intermittent. He continues with the monthly Lupron and has also had his first infusion of Pluvicto a few weeks ago. The hot flashes have returned with a vengeance, and I'm wondering why? He is metastatic castrate resistant. Thank you!