I can reproduce this.

glassfish-el is in the fedora repository (which makes this whole thing easier to reproduce, because that repo never changes)

https://dl.fedoraproject.org/pub/fedora/linux/releases/31/Everything/x86_64/os/Packages/g/glassfish-el-3.0.1-0.11.b08.fc31.noarch.rpm

The repomd.xml file points to the correct primary.xml, with the right sha256: https://dl.fedoraproject.org/pub/fedora/linux/releases/31/Everything/x86_64/os/repodata/87aea7fb189357f558fad367a3882383cb8804a6e666b2ad655b4321a75069f7-primary.xml.gz

The primary.xml file contains what appears to be valid metadata for the package:

```
<package type="rpm">
  <name>glassfish-el</name>
  <arch>noarch</arch>
  <version epoch="0" ver="3.0.1" rel="0.11.b08.fc31"/>
  <checksum type="sha256" pkgid="YES">13843f865456149e0d37f0d68ab002d48984c21f7f67c4a0cf94b06590e867e8</checksum>
  <summary>J2EE Expression Language Implementation</summary>
  <description>This project provides an implementation of the Expression Language (EL).
The main goals are:
 * Improves current implementation: bug fixes and performance improvements
 * Provides API for use by other tools, such as Netbeans</description>
  <packager>Fedora Project</packager>
  <url>http://uel.java.net</url>
  <time file="1564462535" build="1564036410"/>
  <size package="172872" installed="192559" archive="193148"/>
  <location href="Packages/g/glassfish-el-3.0.1-0.11.b08.fc31.noarch.rpm"/>
  <format>
    <rpm:license>CDDL-1.1 or GPLv2 with exceptions</rpm:license>
    <rpm:vendor>Fedora Project</rpm:vendor>
    <rpm:group>Unspecified</rpm:group>
    <rpm:buildhost>buildvm-19.phx2.fedoraproject.org</rpm:buildhost>
    <rpm:sourcerpm>glassfish-el-3.0.1-0.11.b08.fc31.src.rpm</rpm:sourcerpm>
    <rpm:header-range start="4504" end="8840"/>
    <rpm:provides>
      <rpm:entry name="glassfish-el" flags="EQ" epoch="0" ver="3.0.1" rel="0.11.b08.fc31"/>
      <rpm:entry name="mvn(org.eclipse.jetty.orbit:com.sun.el)" flags="EQ" epoch="0" ver="3.0.1.b08"/>
      <rpm:entry name="mvn(org.eclipse.jetty.orbit:com.sun.el:pom:)" flags="EQ" epoch="0" ver="3.0.1.b08"/>
      <rpm:entry name="mvn(org.glassfish.web:javax.el)" flags="EQ" epoch="0" ver="3.0.1.b08"/>
      <rpm:entry name="mvn(org.glassfish.web:javax.el:pom:)" flags="EQ" epoch="0" ver="3.0.1.b08"/>
      <rpm:entry name="mvn(org.glassfish:javax.el)" flags="EQ" epoch="0" ver="3.0.1.b08"/>
      <rpm:entry name="mvn(org.glassfish:javax.el-impl)" flags="EQ" epoch="0" ver="3.0.1.b08"/>
      <rpm:entry name="mvn(org.glassfish:javax.el-impl:pom:)" flags="EQ" epoch="0" ver="3.0.1.b08"/>
      <rpm:entry name="mvn(org.glassfish:javax.el:pom:)" flags="EQ" epoch="0" ver="3.0.1.b08"/>
      <rpm:entry name="osgi(com.sun.el.javax.el)" flags="EQ" epoch="0" ver="3.0.0"/>
    </rpm:provides>
    <rpm:requires>
      <rpm:entry name="java-headless" flags="GE" epoch="1" ver="1.7"/>
      <rpm:entry name="javapackages-filesystem"/>
      <rpm:entry name="mvn(javax.el:javax.el-api)" flags="EQ" epoch="0" ver="3.0.1.b08"/>
    </rpm:requires>
  </format>
</package>
```

As a result, it seems to me that everything is correct on the repository side, and that it is DNF which somehow can't see the package.

glassfish-el also seems to be present in the libsolv cache generated on my machine:

```
$ dumpsolv /var/cache/dnf/fedora.solv
[… snip …]

solvable 12241 (12242):
solvable:name: glassfish-el
solvable:arch: noarch
solvable:evr: 3.0.1-0.11.b08.fc31
solvable:vendor: Fedora Project
solvable:provides:
  mvn(org.eclipse.jetty.orbit:com.sun.el) = 3.0.1.b08
  mvn(org.eclipse.jetty.orbit:com.sun.el:pom:) = 3.0.1.b08
  mvn(org.glassfish.web:javax.el) = 3.0.1.b08
  mvn(org.glassfish.web:javax.el:pom:) = 3.0.1.b08
  mvn(org.glassfish:javax.el) = 3.0.1.b08
  mvn(org.glassfish:javax.el-impl) = 3.0.1.b08
  mvn(org.glassfish:javax.el-impl:pom:) = 3.0.1.b08
  mvn(org.glassfish:javax.el:pom:) = 3.0.1.b08
  osgi(com.sun.el.javax.el) = 3.0.0
  glassfish-el = 3.0.1-0.11.b08.fc31
solvable:requires:
  javapackages-filesystem
  java-headless >= 1:1.7
  mvn(javax.el:javax.el-api) = 3.0.1.b08
solvable:checksum: 13843f865456149e0d37f0d68ab002d48984c21f7f67c4a0cf94b06590e867e8 (sha256)
solvable:summary: J2EE Expression Language Implementation
solvable:description: This project provides an implementation of the Expression Language (EL).
The main goals are:
 * Improves current implementation: bug fixes and performance improvements
 * Provides API for use by other tools, such as Netbeans
solvable:packager: Fedora Project
solvable:url: http://uel.java.net
solvable:buildtime: 1564036410
solvable:installsize: 192559
solvable:downloadsize: 172872
solvable:mediadir: Packages/g
solvable:mediafile: (void)
solvable:license: CDDL-1.1 or GPLv2 with exceptions
solvable:group: Unspecified
solvable:sourcename: (void)
solvable:sourceevr: (void)
solvable:sourcearch: src
solvable:headerend: 8840

[… snip …]
```

I have tried to install eclipse today, that is part of the dnf output (please note I have glassfish-el-api package already installed):

Problem: package eclipse-platform-1:4.11-3.fc31.x86_64 requires glassfish-el >= 3.0.1, but none of the providers can be installed
  - conflicting requests
  - package glassfish-el-3.0.1-0.12.b08.module_f31+6519+12cd0b27.noarch is filtered out by modular filtering
  - package glassfish-el-3.0.1-0.12.b08.module_f31+6793+1c93c38e.noarch is filtered out by modular filtering
  - package glassfish-el-3.0.1-0.11.b08.fc31.noarch is filtered out by modular filtering

This package has changed maintainer in the Fedora.
Reassigning to the new maintainer of this component.

This message is a reminder that Fedora 31 is nearing its end of life.
Fedora will stop maintaining and issuing updates for Fedora 31 on 2020-11-24.
It is Fedora's policy to close all bug reports from releases that are no longer
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