Presuming you already know good IV practices and have no changes to your usual technique, gear, equipment, or frequency of use..:
- Could be some kind of strength/ingredient difference in your gear (mixing with enough water??)
- Could be general circulation system issue.. Any change in exercise/muscle tone? Are you drinking enough water? Eating nutrients?
- Could be nutrient deficiency. This fucked my veins up before. Get your iron, magnesium, etc
- Wear and tear. After 20 years on/off I definitely bruise up 10x worse, even though I use 100x less than back at the start
To heal bruises faster you can use specialty vein cream, or I've been trying hemmorhoid cream as a cheaper substitute. It seems to help but idk if it's actually fine to do or not so..