There are a few things that could cause this -
https://www.healthline.com/health/idiopathic-craniofacial-erythema - This is uncontrolled, excessive blushing. Sometimes, there is a cause - embarrassment, anxiety, etc., but sometimes it is unprovoked.
Rosacea is a skin condition that causes redness and small, pus-filled bumps on your face, usually on the cheeks, nose and forehead. https://www.healthline.com/health/skin/rosacea
There are also some medications that can cause it, so check any meds you might take to see if that's a side effect.
Here are some conditions that you may have if you have other symptoms too - https://www.nhs.uk/conditions/blushing/
Good luck, and let us know if you figure it out!