Previous answer is bad advice.
If the foil lidding is separating it is because of inferior sealing. This could be caused by a few reasons.
My suspicion is that you have purchased clones rather than original Keurig brands. Thermal sealing done by packaging equipment other than Keurig Incorporated can be less reliable.
It could also be a polypropylene compatible issue from a Chinese manufacturer of knock off cups. (Water temperature from brew cycle causes seal to fail)
Either way, there is a high probability that this is a defective cup purchase. If it continues after you try different capsules, please continue thread and I can offer a final suggestion.
Darren