Stirrbar from Temu

So I heated and stirred a solution of copper sulfate to concentrate it at not that high ~150°C. After coming back for a few hours the stirrbar was completely black and weirdly cramped. It seems like it melted cause it also turned the solution dark greenly but as it's Teflon this shouldn't be the case.

Any thought what might happend and if I still should be using the other ones?