In principle, the upload of all possible combinations of file names should be possible, so special characters, spaces, numbers and letters. It is only important to define the position of the user name when uploading.
1234 TEXT -{CODE}- 123456.pdf
TEXT-{CODE}, TEXT2-123456-2022-01-01.pdf
TEXT-{CODE}-TEXT2.pdf
TEXT {CODE} TEXT2.pdf
Here the spaces before/after the user code would not be allowed. Valid would be: TEXT-{CODE}-TEXT2.pdf
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