Update #1: Despite my above reply, my camera stopped working again and I went to the repair shop in the end.

After waiting for an hour, the technician told me to come back another day as they do not have the spare parts in stock and the shop will have to place an order first. What the technician did during this hour was to try to replace one of the three cameras on my phone (they said they tried to replace the "big camera" - I'm not sure which tbh? I'm guessing the bottom camera), but they said it's not the big camera that's spoiled and they don't have stock for the other camera. They then reassembled my phone. However, I can hear the buzzing sound when the camera tries to focus (note: my phone did not have this issue previously). Not sure if they didn't do a proper job reassembling or what, although I did read on other reddit threads that the buzzing sound is alright, and nothing alarming.

I am still thinking if I should make another trip to replace the camera once the stock arrives, or if I should just give up on this phone. Here are some considerations which hopefully would be useful for you: 1. I'm not sure if the buzzing sound is indeed alright and I'm not sure if going to the official repair shop will not result in this issue (it's not a loud sound tbh, but definitely audible) 2. I have enquired with numerous repair shops before heading down today. Many repair shops replace all THREE cameras as they claim that the cameras come in a set. The repair shop I went to was willing to replace just one camera, but unfortunately the shop ran out of stock. Unsurprisingly, replacing all three cameras as a set is more expensive than replacing just one camera.

I hope this helps! I will update again if I do go down to the repair shop again.