src/Buttons/BetterButton_SaveAndPrev.php
public function baseTransform()
    {
        parent::baseTransform();
        $disabled = (!$this->gridFieldRequest->getPreviousRecordID());

        return $this->setDisabled($disabled);
    }
public function baseTransform()
    {
        parent::baseTransform();
        $disabled = (!$this->gridFieldRequest->getPreviousRecordID());

        return $this->setDisabled($disabled);
    }
Updates the button to be disabled if there is no previous record
@return FormAction