When there’s something different between two files but you just cannot see it — xxd is a command line hex dump utility. You can even pair it with diff to see … oh, one has \r\n and the other just has \n
[lisa@FVP05 ljr]# diff -u <(xxd unix.txt) <(xxd dos.txt)
--- /dev/fd/63 2025-01-15 16:39:58.016083028 -0500
+++ /dev/fd/62 2025-01-15 16:39:58.018083031 -0500
@@ -1 +1 @@
-00000000: 4865 6c6c 6f21 0a Hello!.
+00000000: 4865 6c6c 6f21 0d0a Hello!..
