What have I done wrong?

I got an Ender3 V3 SE and the CR-PLA filament from Creality. My settings were 60° bed, 200° nozzle. While the print itself came out well, it was super stuck to the bed. I tried the freezer method, scraping it off (with metal, until I've learned metal lightly scratches this plate XD) but what helped the most was just heating the bed back to 70-80°. Yet a small amount of residue in the picture is desperately stuck, even after trying isopropyl and toothpaste with a toothbrush. I've also not cleaned the board with isopropyl before the print, as I've assumed it's clean out of the box, nor have I used hair spray, glue or anything similar. What have I done wrong, and how can I prevent it in the future?

I got an Ender3 V3 SE and the CR-PLA filament from Creality. My settings were 60° bed, 200° nozzle. While the print itself came out well, it was super stuck to the bed. I tried the freezer method, scraping it off (with metal, until I've learned metal lightly scratches this plate XD) but what helped the most was just heating the bed back to 70-80°. Yet a small amount of residue in the picture is desperately stuck, even after trying isopropyl and toothpaste with a toothbrush. I've also not cleaned the board with isopropyl before the print, as I've assumed it's clean out of the box, nor have I used hair spray, glue or anything similar. What have I done wrong, and how can I prevent it in the future?