the SYD>ADL>DEL service ended on 26th March, I don't recall seeing any notice about this, but the QF website now describes it :
| Asia | Sydney (via Adelaide) <> Delhi Delhi <> Sydney (non-stop)
 | Seasonal service until 26 March 2022 | 
 
Which is now replaced with:
| Asia | Melbourne (via Adelaide) <> Delhi Delhi <> Melbourne (non-stop)
 | Now flying | 
 
So the ADL>DEL>PNQ option is viable, BUT
Even the Indigo website timetable looks all screwed up. Perhaps they're respectively updating things? lets call it a conjunction of Indian IT technology and Qantas' airline strategy on display.