Joist hangers are U shaped metal supports that take the load of a floor joist that meet a ledger board at a 90 degree angle and transfer them to the ledger board that is supposed to be secured to the home structure with bolts. The left single joist hanger is installed and will take the weight placed upon that floor joist and transfer it to the ledger board just like it is supposed to.
When the contractor ordered the floor joist hangers it would appear they forgot to order double joist hangers for the end joists. What was done here is the contractor just left out the part they did not order and incorrectly installed just one single joist hanger where the double joist hanger was supposed to be installed.
Exactly half the weight the double joist hanger was supposed to transfer is now being transferred to the ledger board. While a catastrophic collapse of the deck structure is not likely corrective actions are still necessary in order to avoid movement of the deck structure that can be unsafe and hazardous.
When conditions like these are found a skilled home inspector will warn his client it is not likely the necessary permits, inspections and approvals were obtained and that the real estate taxes may not have been updated either.
In any case in order to avoid the risk of property damage and personal injury do NOT use the deck until it is made safe. Because the existing deck does not meet modern standards for safety. Additional defects must be expected to exist. During a visual inspection like the one performed today I am not able to determine if proper and adequate footings exist or (sometimes) that the deck is adequately secured to the home. Hidden water problems and other hazards may very well exist that we could not see or report on today. Please realize decks can and do fail without warning causing personal injury. PRIOR to expiration of your home inspection contingency, further evaluation and corrective actions are necessary in order to avoid personal injury. PRIOR to expiration of your home inspection contingency you must also obtain written verification from the municipality the required permits, inspections, approvals and real estate tax updates were obtained OR obtain them.