Sewer odours inside can suggest a dry catch, split air vent

https://www.pitchero.com/clubs/eyelsh/news/common-plumbing-leaks-that-you-may-experience-2923600.html

Drain odours inside can suggest a completely dry catch, cracked vent, or partial clog; Geelong homes with large trees or older sewage system lines might need CCTV inspections to find breaches and stop repeating scents.