I'm not sure of the origin of meeting "parking lots" but they have no rightful place in the Agile Canavs process. The parking lot idea as practiced is simple. The people running a meeting label something they deem unworthy of discussion. They put it on a list that often mothballs the idea into quiet extinction unless the idea originator argues its way back into competitive existence on the list of worthy ideas.
The obvious benefit of parking lots is to create focus, yet at an opportunity cost of potentially losing important considerations and to lose engagement of people whose ideas fated to the parking lot.
In the Agile Canvas process, every single voiced object is listed somewhere. There is literally a place for anything and everything that could come up in the process. And on the questions, stories and sprint lists, they are sequenced according to the order in which we will take action on them. We make sure we lose nothing because change is a constant and what we assumptively declare trash today might become treasure tomorrow.