TYPO3 Core

Typo3 is adding prefix [Translate to XXX:] to all text fields upon making a translated copy of content.

There is TCEMAIN.translateToMessage config option, but it only allow to change prefix, not suppress it.
Config option
TCEMAIN.translateToMessage =
is the same as absence of option at all.

As seen in code (class.t3lib_tcemain.php, line 3795)

if (isset($TSConfig['translateToMessage']) && strlen($TSConfig['translateToMessage'])) {
$translateToMsg = @sprintf($TSConfig['translateToMessage'], $langRec['title']);
}

if (!strlen($translateToMsg)) {
$translateToMsg = 'Translate to ' . $langRec['title'] . ':';
}

$overrideValues[$fN] = '[' . $translateToMsg . '] ' . $row[$fN];

field will get prefix in any case.