It is a bug indeed.
vue-loader will search all rules which matches foo.vue first, if not found, it will try to match foo.vue.html.
While plugin for webpack 5 does not traverse all rules. It matches .vue then .vue.html with a single rule. @18566246732

When you use "webpack v5.0.0", if you encounter "error error: [vueloaderplugin error] no matching use for Vue loader is found. Make sure the rule matching. Vue files include Vue loader in its", If other loaders appear before "Vue loader", for example, "HTML loader" appears before "Vue loader", then just add an "enforce" option in the rules of "HTML loader", and its value is the string "post". In this way, the original loader can be used normally without changing the order of the original loader.
The configuration example code is as follows:

module: {
rules: [

// first loader
{
test: /.(html|htm)$/i,
enforce: 'post',
use: [
{
loader: 'html-loader',
},
],
},

// other loader...

{
test: /.vue$/i,
use: [
{
loader: 'vue-loader',
},
],
},

],
}

Today, while updating the configuration of webpack 5, I explored this problem and verified that this method is ok.