Default is “the maximum msats worth of HTLCs that can be pending (or in-flight) on our side of the channel.” And `lncli openchannel —remote_max_value_in_flight_msat` allows you to adjust beyond that default upon channel open.

https://github.com/lightningnetwork/lnd/commit/a66a1e113fb04912ac2e8ae62446bce8fed8d12a