8027:20181106:232953.095 Uncompressed message size 6902047 from hostA exceeds the maximum size 134217728 bytes. Message ignored.
8027:20181106:232953.096 cannot obtain configuration data from server at "hostA":

This message does not make sense, and the reason for that is it is showing the expected_len instead of the reserved size, which it is actually checking, retrieved from the PDU to indicate the size of the compressed data uncompressed.

Looks like an honest copy and paste bug from the uncompressed section above it, where it does compare ZBX_MAX_RECV_DATA_SIZE to expected_len.

[https://github.com/zabbix/zabbix/blob/trunk/src/libs/zbxcomms/comms.c|Lines 1664 - 1673]

/* compressed protocol stores uncompressed packet size in the reserved data */

if (0 != (protocol_version & ZBX_TCP_COMPRESS) && ZBX_MAX_RECV_DATA_SIZE < reserved)
{
zabbix_log(LOG_LEVEL_WARNING, "Uncompressed message size " ZBX_FS_UI64
" from %s exceeds the maximum size " ZBX_FS_UI64
" bytes. Message ignored.", (zbx_uint64_t)expected_len,
s->peer, (zbx_uint64_t)ZBX_MAX_RECV_DATA_SIZE);
nbytes = ZBX_PROTO_ERROR;
goto out;
}