UpdateChecker can't find the plugin itself because it doesn't have the same author as the one listed on Umod, you can just add the correct link to the plugin and then the check will be done by the link
Just change from this
{
"Name": "Metabolism",
"Author": "Orange",
"Plugin version": "1.0.0",
"Link to plugin": "https://umod.org/plugins/no-metabolism",
"Marketplace": "uMod",
"Ignore": false
},
TO
{
"Name": "Metabolism",
"Author": "Orange",
"Plugin version": "1.0.0",
"Link to plugin": "https://umod.org/plugins/metabolism",
"Marketplace": "uMod",
"Ignore": false
},