TYPO3 Core

here is the error:
An exception occurred while executing 'INSERT INTO `index_words` (`wid`, `baseword`, `metaphone`) VALUES (?, ?, ?)' with params [246923395, "\x70\x72\x65\x76\x69\x65\x77\x5f\x75\x6b\x76\x76\x61\x30\x31\x5f\x5f\x6b\x6f\x72\x72\x65\x6b\x74\x75\x72\x5f\x5f\x76\x6f\x72\x62\x65\x75\x67\x75\x6e\x67\x73\x5f\x75\x6e\x64\x5f\x76\x65\x72\x62\x65\x73\x73\x65\x72\x75\x6e\x67\x73\x6d\x61\xc3", "268043616"]: Incorrect string value: '\xC3' for column 'baseword' at row 1

the indexing had an error because in this line of code here:
[[https://github.com/TYPO3/TYPO3.CMS/blob/9827a72a8bf71d32e25261638f65190f59d071bc/typo3/sysext/indexed_search/Classes/Indexer.php#L1078]]

$val = substr($val, 0, 60);

the string had a special character at exactly the position 60 and was broken by the cut
after replacing the line with teh following it worked for me again

$val = mb_substr($val, 0, 60);