Bubbles under a screen protector are usually caused by dust or air getting trapped during fitting — this is an application issue rather than a product defect.
How to fix it
Carefully peel back the screen protector
Clean your screen thoroughly with a lint-free cloth — make sure it's completely dust-free
Reapply the protector slowly from one edge, pressing out air bubbles as you go
If it arrived with bubbles or adhesive issues
If the screen protector arrived with a defect (adhesive not sticking, bubbles that appear without dust) rather than a fitting issue, get in touch with a photo and your order number. If it's a product fault, we'll replace it under warranty.