Incorrect display with 'compressionLevel' = 9 and config.compressCss = 1

Our servers are configured to automatically compress websites.

For performance reasons, it also makes sense to compress the website's CSS and JS files via TypoScript with

config {
    concatenateJs = 1
    compressJs= 1

    concatenateCss = 1
    compressCss = 1
}

to compress and summarize.

If you now additionally use the compressionLevel in the install tool/the file "typo3conf/LocalConfiguration.php" with

$GLOBALS['TYPO3_CONF_VARS']['FE']['compressionLevel'] = 9; // or value > 0

the site is compressed, the files that have already been compressed via TypoScript are also compressed. This destroys them and they can then no longer be read by the browser.

For a website hosted by us, the compressionLevel can therefore be set to "0".