How did this happen?

How did this happen? What did I do wrong? The temperature in my house is warm, I mixed everything for 5 minutes, and a couple more for good measure when I mixed the colors in, then I let it sit a bit for bubbles. Then poured over the white squares and went to demold today and it’s stuck in some places and tore a hole in my mold. If wondering brand, I use Magic Resin from Amazon. But I’ve made 2 sets prior and this didn’t happen. I’m really new to this, I’ve only been playing with resin since November

How did this happen? What did I do wrong? The temperature in my house is warm, I mixed everything for 5 minutes, and a couple more for good measure when I mixed the colors in, then I let it sit a bit for bubbles. Then poured over the white squares and went to demold today and it’s stuck in some places and tore a hole in my mold. If wondering brand, I use Magic Resin from Amazon. But I’ve made 2 sets prior and this didn’t happen. I’m really new to this, I’ve only been playing with resin since November