Every host that can run this customer's VMs is full (after failover headroom) — the fleet has aggregate capacity but no single host has room for the next VM. This is fragmentation, not a too-big spec.
Buy another host that serves this class, or free capacity (evict/rebalance/migrate a VM off a packed host); the shortfall places automatically once one host has room.
The Capacity lens shows the largest free single-host slot vs the requested spec. It recovers on the next recovery sweep once room exists.
