Cellulose insulation is typically an insect inhibitor. Boron and other additives are used to resist fire, insects, dust, etc...

It can act to reduce the air flow through fiberglass insulation if blown in as a top layer.

https://www.attainablehome.com/cellulose-insulation-pros-and-cons/

https://cellulose.org/Cellulose-Insulation-2nd.php?pagename=DispellingMyths&dirname=HomeOwners

My choice for insulation is ' rock wool '.

https://www.jay-k.com/10-benefits-of-rockwool-insulation/