As @sweh pointed out, the point release versions are just a point of time. The moment 8.5 drops, 8.4 is no longer supported and a dnf update will bring you to the latest. We only support what is latest and current as released by upstream and us.
RHEL has generally had a 10 year lifecycle on a release where the first 5 years is fully supported (which is generally two point releases a year) and then goes to maintenance mode for the last 5 years where X.9 is the final (RHEL 5 and 6 are notable exceptions to this, 5 ended with 5.11, 6 ended with 6.10).
Myself and other leads have talked about putting a clarifying page on how the EOL generally works. The red hat policy page actually goes over how they do it and we generally follow the same idea (sans EUS and supporting point releases older than what’s current).
Below is sort of an example. This isn’t perfect and is more of a projection based on how releases have historically happened. For the sake of the example, I threw in when expected future EL drop times, which historically is around the .6 of the current production release. (EL9 and EL10 are just examples and are likely not accurate, but the EL8 should be pretty close to accurate). This tries to follow the “every 3 years” plan that Red Hat has said they would be doing going forward.
