Could you clarify your issue? What's missing? What's unneeded?

FYI, plasma-oxygen is already not installed by default, so I'm curious what the ask is here.

ah ok, I was thrown off by the initial statement:
"The Oxygen theme is provided by the package plasma-oxygen."
which appears to be untrue (at least in part).

rpm -q -f /usr/share/plasma/desktoptheme/oxygen/
kf5-plasma-5.90.0-1.fc35.x86_64

We could consider splitting that out I suppose, wonder why upstream chose to put it there rather than in plasma-oxygen

FYI, plasma-oxygen is already not installed by default, so I'm curious what the ask is here.

The package is not installed by default, but the theme is, somehow. Here's a screenshot of a live environment of the "Fedora-KDE-Live-x86_64-35-1.2" ISO:

Could you clarify your issue? What's missing? What's unneeded?

Breeze is the one maintained now, not Oxygen.

Edit: I had to repost the comment because I couldn't upload the screenshot when editing the previous comment.

ah ok, I was thrown off by the initial statement:
"The Oxygen theme is provided by the package plasma-oxygen."
which appears to be untrue (at least in part).

rpm -q -f /usr/share/plasma/desktoptheme/oxygen/
kf5-plasma-5.90.0-1.fc35.x86_64

We could consider splitting that out I suppose, wonder why upstream chose to put it there rather than in plasma-oxygen

Understood. Also, the Air theme is provided by the same package you mentioned:

$ rpm -q -f /usr/share/plasma/desktoptheme/air
kf5-plasma-5.89.0-1.fc35.x86_64

Edit: it seems that Air can't be removed right now: https://bugs.kde.org/show_bug.cgi?id=438358
According to Nate Graham, it's fine to remove Oxygen, which is already provided by the plasma-oxygen package: https://bugs.kde.org/show_bug.cgi?id=438180#c4

The problem here is that the Oxygen and Air Plasma themes inappropriately live in the plasma-framework repo. Since plasma-framework is necessary for Plasma, everyone gets those themes installed too. See https://bugs.kde.org/show_bug.cgi?id=452133.

The correct upstream resolution would be to remove them from plasma-framework and into the Oxygen repo. However those repos don't share release scheduled (plasma-framework is in Frameworks, Oxygen is in Plasma), , so there would be a period of time during which the files were either missing, or duplicated in packaging. This would also break people who currently use the Oxygen theme without having the Oxygen package installed. It's probably a small group of people, but that's a currently-working use case that would be broken.

As a result, we will probably have to wait until KDE Frameworks 6 to resolve this issue.