Adicionar essa configuração para evitar highlight de erros de indevidos :

"intelephense.telemetry.enabled": false,
"intelephense.completion.triggerParameterHints": true,
"intelephense.completion.insertUseDeclaration": true,
"intelephense.trace.server": "messages",
"intelephense.diagnostics.undefinedClassConstants": false,
"intelephense.diagnostics.undefinedFunctions": false,
"intelephense.diagnostics.undefinedConstants": false,
"intelephense.diagnostics.undefinedProperties": false,
"intelephense.diagnostics.undefinedTypes": false,
"intelephense.diagnostics.undefinedMethods": false,