Welcome to the Bunnings Workshop community @junyouli. It's sensational to have you join us, and many thanks for your question about garden pests.
Given how much has been eaten, I suspect it's likely rats or possums, as they're both known to chew on rose shoots and flowers if accessible. I'd suggest putting your plants up off the ground and in a location that's harder for anything to access. Alternatively, you might consider a small greenhouse that will provide convenient shelves and offer warmth and protection for your plants.Please let me know if you have further questions.
Mitchell
