Hi mummies, can playpen be an alternative to a baby cot for infants/newborns? Any factors to consider for such a playpen?

We bought a playpen for baby before he is born. The rooms in new hdb flats r very small. Tatz y we bought playpen instead of cot. We didnt know he is a tall baby n he loves lift up both legs & slam both them down. The playpen shakes vigorously. Lol. When he was 4 months old, we kept e playpen as it was a concerned for us. We r scared tat e playpen would collapse (of cos it wont easily collapse). Anyway, he is tall & big size, so we let baby slp on single size adult mattress which is put on e floor instead.