Things Moving in my Lateral Flow Test Swab

Using my Chinese made cheap eBay microscope, I magnified the tip of my Chinese made lateral flow test kit swab. This Covid 19 self-test kit also known as Rapid Antigen Test was issued to me while working in a primary school in Cambridgeshire England in 2021. The black fibres move when you breath on them. They are not alive as such as they coil up while breathing in them then slowly return to their original position when my breath is removed. They are either reacting to heat or moisture from my breath. On later issued kits from a Cambridgeshire pharmacist, the black fibres were still present but didn’t react to breath. Can anyone explain why the fibres are moving in my earlier kit lot number X2012714 manufactured 14th December 2020.