For every MWh of generation IFN produces they get 1 LGC...

For every MWh of generation IFN produces they get 1 LGC certificate. IFN has forward sold a lot of their LGC certificates at a higher price but it's likely that the falling prices will affect their next lot of agreements.

"Morgans analyst Nathan Lead noted that about one-third of Infigen's generation is sold into the National Electricity Market at spot prices, while its exposure to spot LGC prices is due to rise to 78 per cent in 2021-22, from 23 per cent this year." - AFR

So as the LGC price falls their margin will fall, how much depends on how much they forward sell/hedge their LGC certs but it will no doubt affect them more.