The official 0.15.0 has been released, but the error continues to occur.
dfx deploy --network=playground
Error: Failed to create AgentEnvironment.
Caused by: Failed to create AgentEnvironment.
Network not found: playground
It seems that dfx deploy --playground is not available.
dfx deploy --playground
error: unexpected argument '--playground' found
tip: to pass '--playground' as a value, use '-- --playground'
Usage: dfx deploy [OPTIONS] [CANISTER_NAME]