Yeah, that's an elastic IP, check under EC2.

People forget to clean them up after shutting down the instance (probably kept in case you want to keep your IP)

It's crazy that it's so common, but that they wouldn't make that obvious.

Considering the whole IPv4 extinction that's coming down and all.

So an elastic IP is just an AWS provided IP that they hand over to you... it's free while your instance is running but if you stop your instance, you get a small bill (it's like $0.84 a month)

I will gladly welcome the eventual IPv4 extinction, but unfortunately I'm pretty confident it won't happen for another 30 years.

I don't have any elastic IPs. The only thing under EC2 is a security group that it won't let me delete, but seems like no resources. My bill this month is $2.88 /shrug

Check volumes, non-root volumes are kept on deletion but should be EBS charged instead.

What does the bill details screen show? I manage an AWS bill and I find it overly detailed. Others mentioned leftover EIPs, but the bill shows these as their own line item.

Not saying it can't happen, but I've never seen an 'Other' listed on the bill details screen. As I said above, it's detailed to a fault.

Actually it looks like this is for an EBS snapshot. Now it seems like EBS is a Lightsail feature, and the Lightsail console says that I don't have any storage or snapshots? Hm

EBS is also the general external storage attached to an instance. Go the ec2 console and look at snapshots and you should see it there. They are region specific, so make sure to select the region referred to on the bill.

I haven't used Lightsail, so I'm not sure if those snapshots end up in the general ec2 console. But, if you already checked the LS console and didn't see anything, then they must be in the ec2 console.

Possibly a disassociated elastic IP address?