wdiff is broken when the input contains a null character.
For instance, create 2 files a and b with

  printf "a\n2\n3\n4\n5\n6\n7\n8\n" > a
  printf "b\n2\n3\n4\n5\n6\n7\n8\n\000\n" > b

$ wdiff a b
b
2
3
4
5
6
7
8

instead of something like

[-a-]{+b+}
2
3
4
5
6
7
8
{+^@+}

Similarly, the following is incorrect:

$ diff -au a b | wdiff -d
++ b    2024-02-09 14:11:23.981863795 +0100
@@ -1,4 +1,4 @@
b
2
3
4
@@ -6,3 +6,4 @@
6
7
8

There is no such issue if I replace \000 by \001.
So this is specific to the null character.