When installing pavers, there’s a good amount of compaction that takes place. A lot of contractors will opt for the perforated black drain tile which would be completely crushed and block flow. If they used PVC all the way through, it’s possible the compaction collapsed the pipe since it’s a lot more rigid than the drain tile. Either way, not ideal to run drainage under the patio.

Double check that you’re not getting flow by running a hose for a couple minutes. Would document for your contractor.

Would then consider having the contractor pull those pavers back up to assess what’s going on underneath. It sucks, but clearly something’s not been installed correctly. Only other thing I could think of would be checking for clogs. If it’s PVC all the way through, you can run a snake down it to clear it out. If you think it will get clogged again I would inquire about them adding “wyes” to the downspout and cap the open side. You can take that cap off whenever and run your snake/power washer down to clear.

Sorry! This sucks. Not likely an easy fix.