Blurry pictures uploaded to Facebook and Instagram. Can't find a fix. I have a theory.

Hello, so for years I've been anti apple and decided to take the plunge with a 12 pro max. Regrets. Anyway, I bought the 256gb version. The 1st few days of owning it my posted pictures were clear and perfect. Once I hit the 5gb icloud storage the uploads to Facebook and Instagram became blurry. Now when I sent my husband the pictures, the pictures that look blurry for me, are crystal clear when he uploads them. He pays monthly for extra storage (even though his phone still has space!). I have checked the settings in my iPhone and Facebook, they are both set to HD upload. I have unistalled and reinstalled the apps. Nothing works. So I'm assuming it's because I have reached 5gb of icloud storage and icloud is what optimizes the photos? Am I wrong? What can I try? I've done alot of fiddling with the phone and apps and googling. Nothing works. Please help.