• VSCode Version: 1.47.2 (user setup)
• OS Version: Windows_NT x64 10.0.18362

Steps to Reproduce:

1. Create a file named jsconfig.build.json in any directory.
2. Open the file with VS Code.
3. The file is opened with the "JSON" language mode (instead of the expected "JSON with Comments" mode).

Other file names, e.g. jsconfig.test.json, are also opened in "JSON" language mode.

In contrast, tsconfig.json is opened in "JSON with Comments" mode even if the file name contains suffixes, e.g. tsconfig.build.json.

Does this issue occur when all extensions are disabled?: Yes