The issue you are facing is that you are hitting the MaxItemNameLength length, which by default is 100:

<!--
  MAX ITEM NAME
            Specifies the maximum length of an item name.
            Default value: 100
      
-->
<setting name="MaxItemNameLength" value="100"/>

Sitecore will "sanitize" the item name based on the file uploaded so ensure it meets various criteria (MaxItemNameLength and InvalidItemNameChars) if not it will strip those characters and shorten the item name.

Either increase this to a higher value or shorten the name of the media item that is uploaded.

The issue you are facing is that you are hitting the MaxItemNameLength length, which by default is 100:

<!--
  MAX ITEM NAME
            Specifies the maximum length of an item name.
            Default value: 100
      
-->
<setting name="MaxItemNameLength" value="100"/>

Sitecore will "sanitize" the item name based on the file uploaded to ensure it meets various criteria (MaxItemNameLength and InvalidItemNameChars), if not it will strip those characters and shorten the item name.

Either increase this to a higher value or shorten the name of the media item that is uploaded.