A Job Variable get the size of a file with {FILE(Size|C:\temp\test_file.txt|B)}
The Job Variable is set to '32 ' (So a lot of spaces at the end)
Assigning with {STRING(TrimChars|{FILE(Size|C:\temp\test_file.txt|B)}| )}
give still the same result with spaces at the end.

How can I remove that spaces?

If an "user variable" of type "string" is used instead of a "job variable", it seems to work.