Sudden addition of VPC charges on EC2 bills

Why did I get new charges on my t3.micro instance? I noticed my EC2 billing got VPC charges since Feb which was new, I did not see VPC charges before. The instance is t3.micro and I use it to host my simple website with just a few pages. I have not touched it for a long time, not made any changes to the instance nor to my account. The additional charge of VPC was about 30% increase from previous months' cost that did not have VPC charge.