It always was even before the Fenton Portal, just more subtle, cold spots, newer electronics not working properly, older picking up things that weren't always there, things at the periphery that you can't see when you turn, shadows too dark, lights too dim.

Lake Eerie was named that for a reason. they knew to never swim alone, or at night without lights.

Then the portal happened and those who didn't adapt left. then the invasion and they thought they are going to just go back to new normal and...

The town refused to leave. Not the people the town itself, turned out Amity had a city spirit and she liked it in the Zone so they adapted, 'parkers always adapted if they didn't they left, this side of the veil or the other.

They managed to coax Amity to return and continued living, a little to the left, teeth a little too sharp, eyes a little too intense, hearing a little too good, but they adapted. They found out more ghost culture in the zone, some learned to fight, some decided not to. They weren't bothered by property damage anymore, the buildings would pull themselves back together and they would help.