Fatal error on Joomla 6

Hello, i have a problem on my J6.1.1 install :Environment: Fatal "Mbstring::mb_trim()" UndefinedMethodError on Joomla 6 when loading any admin view that uses an Omnipay payment plugin
I tried to post the feedback here but always blocked by suciri, so i posted it inside a word file file
Thanks

Hi Olivier

Look like one folder could not be deleted automatically during installation/update of the extension for some reasons and it causes the error

Please check and make sure libraries/omnipay3/vendor/symfony/polyfill-mbstring folder is removed from your site and the error will be gone

Regards,

Tuan