Well, facebook shorts have plenty of people doing exactly this in their "amazing crafts" videos where a dude usually does something extremely stupid and hazardous. I eyeroll when one pops up now
I was going to say it might be junk solder, but the brand looks well reviewed. Maybe counterfeit? I just had to deal with a kid's first soldering kit containing "solder" with no listed alloy percentages. Couldn't solder worth a damn.