I've deleted everything but im still getting billed $4 a month

Lightsail billing applies to all active resources, not only to instances. Even after an instance and its associated snapshots have been deleted, other resources such as static IP addresses, DNS zones, or attached block storage volumes may remain and continue to generate monthly charges. The standard entry‑level Lightsail plan is billed at a fixed monthly rate of approximately USD 5, which corresponds to the recurring charge of about USD 4 that you are observing.

https://docs.aws.amazon.com/lightsail/latest/userguide/delete-an-amazon-lightsail-instance.html

https://docs.aws.amazon.com/lightsail/latest/userguide/amazon-lightsail-frequently-asked-questions-faq-billing-and-account-management.html

https://repost.aws/questions/QUXTceGm-iTe6ewBHIN6NrBQ/why-am-i-being-charged-for-a-stopped-amazon-lightsail-instance

Check you invoice - it will tell you the services that's incurring the charges. Also, check Cost Explorer - https://aws.amazon.com/aws-cost-management/aws-cost-explorer/features/ - you figure the services that is resulting in the charges.