Not sure it really helps. Have tested with izumi-reflect 2.2.1 - still fails.

I think you may need to override the dependency version. I was able to replicate your issue with izumi-reflect-2.2.0 but not with changing the ZIO dependency to izumi-reflect-2.1.3 or izumi-reflect-2.2.1.

Hm, have tested it in 3 ways, all unsuccessfully.

First with scala-cli snippet.

//> using scala "3.2.0"
//> using lib "dev.zio::zio:2.0.3"
//> using lib "dev.zio::izumi-reflect:2.2.1"
//> using lib "dev.zio::zio-metrics-prometheus:2.0.0"

Second with

dependencyOverrides ++= Seq(
      "dev.zio" %% "izumi-reflect" % "2.2.1"
    ),

Third with rebuild zio with these changes locally and set this version in project.

I tried:
zio 2.0.3 with izumi-reflect 2.2.0 ... and
zio 2.0.4 with izumi-refect 2.2.1, both are UNSUCCESSFUL.
zio 2.0.0-2 with refect 2.1.3, are OK.

I suspect recompiling zio with newest reflect 2.2.2 will fix that. @adamgfraser @celetium - this looks like breakage from compatibility change in scala 3 prefix hanling int2.2.0 - https://github.com/zio/izumi-reflect/releases/tag/v2.2.0 - and there's another fix to prefixes in 2.2.2. so you want to update to that instead. https://github.com/zio/izumi-reflect/releases/tag/v2.2.2

@neko-kai Thanks! Just submitted a PR to upgrade to the latest izumi-reflect version.

@celetium You need to upgrade to the latest version of zio-metrics.