Welcome to the holidays!
After many a slumber party, my kid told me the air mattress had developed an annoying slow leak. I used this patch kit.
The guy in the video found his leak a lot faster than I did. A LOT. Sigh. I used a spray bottle of soapy water. I used a safety razor to shave the fuzz off the mattress.
Tear-Aid Repair Type B Vinyl Inflatable Kit via Amazon