Multiplexed stream are always sending packets by batch of 4,096 bytes

[nicodeslandes]

Command: dotnet run --no-build -- -mux localhost:2202 -l 443 -ssl -sni

Result:

[23:49:41 INF] Read 26280 bytes from multiplexed stream 1
[23:49:41 INF] Sending 4,096 bytes from www.bbc.co.uk:443 to 127.0.0.1:60939...
[23:49:41 INF] Sending 4,096 bytes from www.bbc.co.uk:443 to 127.0.0.1:60939...
[23:49:41 INF] Sending 4,096 bytes from www.bbc.co.uk:443 to 127.0.0.1:60939...
[23:49:41 INF] Sending 4,096 bytes from www.bbc.co.uk:443 to 127.0.0.1:60939...
[23:49:41 INF] Sending 4,096 bytes from www.bbc.co.uk:443 to 127.0.0.1:60939...
[23:49:41 INF] Sending 4,096 bytes from www.bbc.co.uk:443 to 127.0.0.1:60939...
[23:49:41 INF] Read 24887 bytes from multiplexed stream 1

Why are messages split in 4,096 bytes? The batch size should be 65,536.