Beko CRFG3582W_WH Fridge Freezer – water deposit

Hello.
I bought this fridge freezer in march and it has been running well. Over a month ago though it started to buzz very loudly when the condenser was on (I think). I found out this was a vibration issue because when I moved it slightly and adjusted the feet the buzzing stopped. It always seems to come back however I adjust the feet and I have accepted that it will make this noise moving forward. It is situated in my kitchen next to the outside wall where there is a small window and next to the door to the garden which is open regularly. I’m thinking maybe the regular change of ambient temperature may have it running more often. does anybody have any tips on how to stop the buzzing?

Onto the next issue… My partner recently moved the fridge because she thought she hears a mouse behind it and found that the water deposit in the back was totally full. Is this normal? Also I the pictures you can see a kind of foil piece that looks a little bit broken and I’m wondering if someone could help identify this and let me know what it is and if there is a problem with the fridge. Maybe the buzzing is related to this?

Many thanks in advance.
Owen.