For quite a few years I have been using a product called Tear Mender.I patch blue jeans, tents,my winch cover, nylon saddle bags, just about anything fabric or leather. I have never had a patch come off of blue jeans after they have been washed many times. Dries in 15 minutes. Sort of a latex glue
I buy mine at Ace Hardware, 6 oz is about $6 -$7
https://tearmender.com/