What does the system mean by pending transactions when ending a service provider relationship?

We are currently testing out changing the service provider relationship (end dating and starting a new one).

When we do this the system flashes up the warning "Setting the service provider relationship to inactive may impact access to transactions so you should close pending transactions."

So far in our testing we have been unable to determine what a pending transaction is from the payables perspective. All functions we have tested within payables seem to be working as they were before.

Are we looking in the right place or would this impact an area downstream such as cash management / reconciliations?