This commit e17a634 marks a breaking change (introduced in 4.0.7)

Setup:

Search path: /path/to/linked-folder/*/
This is a path to a symlink to /path/to/actual-folder/

Calling code:

$finder
    ->name('ext_emconf.php')
    ->followLinks()
    ->depth(0)
    ->ignoreUnreadableDirs()
    ->in($packageBasePath);

foreach ($finder as $fileInfo) {
    echo $fileInfo->getPathname() . PHP_EOL;
}

Output with symfony/finder 4.0.6:

/path/to/linked-folder/foo/composer.json

Output with symfony/finder 4.0.7:

/path/to/actual-folder/foo/composer.json

While it can be argued, that \Symfony\Component\Finder\SplFileInfo now behaves consistently with \SplFileInfo, which always returns the realpath,
it still is a breaking change from a consumer perspective, e.g. when the returned path is validated against a base path (/path/to/linked-folder/), which now fails because the symlinks are resolved by realpath.