TYPO3 Core

Duplicate:
#98394 proposed this feature, but the solution was to implement an event ModifyLanguagePacksEvent, which can be used for the purpose. So it prepared the architecture, but didn't actually supply/solve the feature.

TYPO3 will try to fetch language packs for all installed extensions in all available languages.
This exposes locally installed extensions to the outer world (the language server).
Furthermore, there might be an extension in the wild with same name, leading to unexpected
downloading foreign language packs. Otherwise unnecessary 404 to TYPO3 translation server
will happen.
It would be cool if extensions could be defined to ignore the procedure. E.g. via

Proposed solutions:
a) On extension level, in extensions composer.json:

{
    "extra": {
        "typo3/cms": {
            "updateLanguages": false
        }
    }
}

b) On project level in settings.php, next to defined languages

    'EXTCONF' => [
        'lang' => [
            'availableLanguages' => [
                'nl',
                'de',
            ],
            'preventUpdateForExtension' => [
                'mysitepackage' => ['nl','de'],
                'mycustomerext' => ['*']
            ]
        ],
    ],

Both solutions don't contradict and solve different scenarios. The settings.php solution can be used in every case, the extension composer.json solution might be helpful additionally (e.g. for smaller extensions without FE output or a config GUI, that thus only output labels during exception and need no translation).