Glue or dirt residue on bottom of psa case . Please help

Just purchased this psa card. Has anyone ever seen a residue like this? The case looks fine otherwise. Card too. Cert checks out. Bought from a reputable seller too. But i have over 15 psa cases with none looking like this. I dont see frosting or any cracks. Please help.

imgur.com/a/5BGdFl0