We save our page name to eVar1. What we've noticed since migrating is that on pages where there are events firing e.g. direct call rules or clicks, the number of unique visitors to eVar1 is a great deal higher than the unique visitors to the page name dimension.
There haven't been any changes to the configuration of the events other than having to add in the clear variables action in the Launch rules so that the events string is reset after an event is fired.
When looking at the network calls in real time (network tab, Adobe debugger...), do you see the visitor ID value changing between the page call and the event call(s), or does it stay the same? Is there any custom logic used to generate the event call(s), or do they use Launch's standard "send beacon" action?