This part of popular mechanic article is quite interesting to me:

...A typical OBIGGS system diverts air from the aircraft engine and separates the nitrogen, injecting it into the jet’s fuel tanks. The more inflammable nitrogen present the less flammable oxygen, helping reduce the possibility of fuel tank explosions...

Perhaps I do not understand English so well.

https://www.google.com/url?q=https://www.thoughtco.com/liquid-nitrogen-facts-608504&sa=U&ved=2ahUKEwicwp-Gu6HqAhUKwKQKHctEB_IQFnoECAYQAg&usg=AOvVaw2hxTUqcGAzaAY_vjsyuG2P

Nitrogen is non-toxic, odorless, and colorless. It is relatively inert and is not flammable

https://www.google.com/url?q=https://www.castlegroup.co.uk/guidance/gas-detection/dangers-of-oxygen-and-flammable-gases/&sa=U&ved=2ahUKEwjcp9Ceu6HqAhUUw8QBHeejDq8QFnoECAoQAg&usg=AOvVaw2a1bw-m2Xw7zY9ejdoAcAm

The second alarm is for when the oxygen levels get too high; usually 24%. When oxygen levels are high things become much more combustible

Or they failed to cover up main veaknes of F35.