TYPO3 Core

While uploading file in the backend a div element is generated to forward configuration to the fileuploader js scripts. With upload_max_filesize set to 128M this looks like this:

<div class="t3js-drag-uploader" data-target-folder="1:/" data-progress-container="#typo3-filelist" 
     data-dropzone-trigger=".t3js-drag-uploader-trigger" data-dropzone-target=".t3js-module-body h1:first" 
     data-file-deny-pattern="\.(php[3-7]?|phpsh|phtml)(\..*)?$|^\.htaccess$" data-max-file-size="1.3421773E+8" 
    ></div>

As you can see the max file size output is not integer but of the float type
data-max-file-size="1.3421773E+8"

The uploader js code intepretes it as integer:
typo3/sysext/backend/Resources/Public/JavaScript/DragUploader.js line 76

me.maxFileSize = parseInt(me.$element.data('max-file-size'));

To change the behavior you could modify the output of the data-max-file-size="xx" or change the js intepretation to

me.maxFileSize = parseFloat(me.$element.data('max-file-size'));

I can not download the full core to search for the html output so modifying the js file works for me