The difference is in the character j
in the position 10: its code is 106 in the input, but in your substring it's 1112 (0x458
- see demo).
Your second j
comes from Unicode page 4
ј 1112 458 0xD1 0x98 CYRILLIC SMALL LETTER JE
It looks the same, but has a different code.
Re-typing j
in the substring
fixes this problem.