Hello,
If Your VLANs are not extended to WAN routers, and You don't run ISIS on these VLANs, then it is not a routed traffic.
Likely flood traffic - I reckon at least 0.9Gbps out of 4.9Gbps is flood.
My math is 4.9-(3.5+3.2-1.2-1.5))=0.9
And 4.9-0.9=4 is switched traffic that takes suboptimal path.
Things to check:
1/ are VRRP masters/backups in their proper places? Could it be that QFX10K-1 is actual VRRP master for more than 2 VLANs?
2/ MAC table timeout on QFX5K and QFX10K - must be the same as ARP timeout on Your servers
HTH
Thx
Alex