there's only 3 input and 2 output, where address 1PNQDmVYFhofPSBZKonz8RKUhxSFUFrQnN used on both input and output which deviate from the common behavior.
There is no such common behaviour; when "new change addy" option was not opted, then either one of the input will appear in output as well.
Only in rare cases, exchanges/casinos will able to find exact inputs for a required output+fees for a transaction. In most cases, a change addy is needed and when "new change addy" option was not enabled then one addy will appear in both input and output.
And why would exchange/casino send the change to one of customer deposit address? It could add bug or technical complexity, such as accidentally add more balance to user's account when in fact the user never make deposit. Besides, change address feature has been around for very long time and enabled by default even on Bitcoin-Qt. Here are some references link i found from quick search,