VW did change the design of the folding mechanism for the Polo’s rear seats in the current model car; the rear seat cushions are fixed in place and no longer fold up vertically behind the front seats. The back seat backrest doesn’t lie completely flat when it’s folded because it folds onto the seat cushion and the height of the rear seat cushion is too high for the folded down backrest to be completely flat and level with the boot floor.
This will be like your new car’s load area;

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I had a 2016 previous model Polo before my 2020 Polo and folding arrangement was different. In tye 2016 car - and I dare say your previous Polos - the rear seat cushions folded vertically up against the backs of the front seats, and the rear seat backs dropped down into the (lower) space normally occupied by the seat cushions. The resultant load space is flat - or virtually flat. Picture below is of a 6c Polo load area;

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