It's because the program you are using to translate IPv6 to IPv4 is wrong. You can't just take the last 4 bytes of an IPv6 address and turn it into IPv4. That's not how IPv6 works.
Yes, I saw you posted this in another thread, checked it, and found that it's just taking the last 4 bytes of the IPv6 address, and turning it into IPv4. That's not correct. Not all IPv6 addresses can be turned into IPv4.
fe80:: means the IPv6 address is a link-local address.
Here's a primer: https://labs.ripe.net/author/philip_homburg/whats-the-deal-with-ipv6-link-local-addresses/
It's because the program you are using to translate IPv6 to IPv4 is wrong. You can't just take the last 4 bytes of an IPv6 address and turn it into IPv4. That's not how IPv6 works.
Yes, I saw you posted this in another thread, checked it, and found that it's just taking the last 4 bytes of the IPv6 address, and turning it into IPv4. That's not correct. Not all IPv6 addresses can be turned into IPv4.
In fact, if you read the code, you see the comment at the top sends you to this Stackoverflow answer: https://stackoverflow.com/a/23147817/11404332
The explanation is there as well.