Oxygen and methane, especially when found together in a planet's atmosphere, have been considered good indicators of the presence of life there. Far less has been heard, ere now, about nitrous oxide as a biomarker. Nitrous oxide (also known as laughing gas) is produced in abundance by living things on Earth. It may be detectable on exoplanets, perhaps even by the Webb telescope, in the near future.

Nitrous oxide can be produced by non-living phenomenon. This is typically found with nitrogen dioxide, though. A marked predominance of Nitrous oxide alone may indicate the presence of life on other planets.

Please find a link to an article on this topic, below:

https://phys.org/news/2022-10-gas-space-life.html