Steps to reproduce:

1. Install Agent 2 (7.0.0beta3) on a host
2. Configure a passive item for the host (does not matter if item works or not)
3. Capture agent traffic (port 10050)

Result:

The (uncompressed) response packets sent by Agent 2 version 7.0.0beta3 have the Reserved field set to the same value as the Datalen field. (For example, if Datalen is 64, Reserved is also 64.

Capture example is attached.

Expected:

Reserved field bytes should be all zeros when compression is not used, according to the protocol specs in https://www.zabbix.com/documentation/devel/en/manual/appendix/protocols/header_datalen .