Are you keeping this tank or planning on replacing it ?
And if you only have 1 circuit to this area, then you don’t have a dedicated E7 or separate supply so the circuit is only a 24 x 7 circuit
Of course it’s man made
Increasing the world population from 2 billion in 1920 to 8 billion in 2020
And then to 9 billion in 2037 can’t be done without consuming vat amounts of resources and energy
All this does is clearly establish the issues with the OP and had they included the photo, very few responses would have been necessary.
Having done countless kitchens, the plan view (top down) is the starting point .......... and as we all know the top down view wasn't a top down view as most...
Your old light is looped at the fitting. Your new light only has connections for switched live, neutral and earth.
So you need to keep the 3 browns connected by a wago or choc block