Looks identical, doesn't match
You paste a product code into a search field and get no result, even though the code looks correct. An extra zero-width space is one possible cause: the visible letters match, but the underlying strings differ.
A similar problem can appear when importing numbers into a spreadsheet. A space used as a thousands separator may not be recognised by the importer. Whether it causes an error depends on the software and its language settings; it does not mean the CSV file is corrupted.
Not every invisible character is unwanted
Documents, web pages, chat messages and generated text can all contain special spaces or formatting characters. Their presence alone does not tell you where the text came from.
Some have a real job. Joiners can be part of an emoji or a written word, and direction marks help mixed right-to-left and left-to-right text display correctly. Removing every invisible character can change the text you meant to keep.
Inspect, clean a copy, then test it
Paste the affected text into MetadataRemover.cc and inspect the findings first. Look for the reported character in the part that fails, such as a product code, a copied link or a numeric field.
Clean a copy and compare it with the original, then try the search or import again. MetadataRemover.cc can flag supported Unicode characters; it cannot know the intended spelling or the rules of every receiving application. Keep the original and check meaningful spacing, emoji and mixed-language text.