My 18 month sleeps with a rif raf comforter. She sucks it to get to sleep and I have recently noticed she stuffs quite a lot in her mouth. Could this be a risk or would she pull it out if she needed? She’s very attached to it and she wouldn’t sleep without it.

Many things that a baby/toddler puts in the mouth can create a choking risk.
If you are concerned about this, then maybe that is a warning sign for you.
Have a look at the info from Product Safety Australia.
https://www.productsafety.gov.au/products/babies-kids/toys/baby-toys

Also Raising Children network has some information about choking risks.
https://raisingchildren.net.au/toddlers/safety/choking-strangulation/choking-prevention