Since kenneling our 8 month old puppy a few weeks ago, he has started getting upset with us when we leave the house. His tantrums are increasing in severity, to the point that today, he broke through his baby gate in his contained area, to break through another one nearby and he peed and pooped on our rug. He hasn't had accidents in the house in months and he hasn't had any issues being left when we go to work since he was weeks old. He hasn't been crated since June and has done perfectly fine. All changes have come since kenneling and quite frankly he's pissed when we leave him. Also, as a side note, he goes to puppy daycare twice per week (and has been for a while now). He absolutely loves going too. Does anyone think this plays into anything that's happening here? Just looking for any insight and ideas on how to reverse this behavior.

I would take it as seperation anxiety. He is probably paranoid that you wont come back. I would probably try leaving for very short times and come right back so he understands that your not leaving him for good. I had to do this with my Libby. I would go outside for 10 minutes and then come back. And each time it was a little longer. She got used to being alone it just took some time and patience.
Good Luck. hope that helps.