You did not sound rude, I just needed more to work with.
As I stated above, source paths of an image are used by Webflow to import the existing image to its CDN, rewriting the source path of a <img> tag to the new Webflow CDN location for the asset. You don’t have the option to block this behavior. That happens automatically with CSV imports where html is mapped to a rich text field.
As such, I would recommend batching your imports into smaller row counts. I personally have not bothered doing large imports since I don’t use Webflow for large CMS collections preferring to handle those on my own platforms. Note: There is no current sync method via CSV import. It is an all or nothing affair. The only alternative being the API.
Feel free to ping me if you need more help. Data is my playground.