AHey everyone! Can you help?! Recently when baking I'm having a lot of trouble with the centre, can you understand why? I used to make great fluffy cakes with the same recipe and I'm now not sure what to do

Could there be a problem with your oven?  do other things cook ok?   have you changed brands of butter or use different pans?  so many variables involved in baking...

It does sound like there might be a problem with your oven.

the other thing to consider are: new batch of any ingredient?  Maybe something is wrong with the flour or sugar or whatever.  It is very heard for us to help you further as most of us are in the U.S and don't use those ingredients or amounts.  Without pictures of what y ou are talking aobut we really are just totally guessing.

Make sure the oven racks are positioned in the middle of the oven. If they are too low or too high it could affect your cakes. I am sure you will figure out what is wrong. Also check your oven thermometer with a mini oven thermometer to be sure oven is cooking at correct temperature.