What should I do if my feet bubble?

Of course it should be broken. First of all, the liquid in the bubble should be discharged. Punch a hole in the surface of the blister with a sterilized sewing needle, put the liquid squeezed from the blister on the table, then smear the wound and its surroundings with disinfectants such as iodine and alcohol, and finally wrap it with clean gauze.

Postscript: You should see if it's your shoes. You'd better wear shoes, sweat-absorbent cotton or socks that fit your feet. Put a' band-aid' on the place where blisters are easy to grind in advance. If possible, you can buy a bottle of anti-foaming (mainly to reduce friction) spray in the store.