Hi
index.php?option=com_jdonation&lang=en"_AND_GTID_SUBSET(CONCAT(0x716a6b7871,(SELECT_HEX((CASE_WHEN_(EXISTS(SELECT_8_FROM_user_usrnm))_THEN_1_ELSE_0_END))),0x71626a7171),6415)--_RcCj=
This indicates that indeed some random bots tried to use a vulnerability in the jDonation extension. None of these attacks worked of course but because you most likely have enabled the "301 redirect from non-sef to SEF" feature under the "Advanced" section of sh404SEF configuration, each of these URLs were recorded (as duplicates).
So the first thing to do is to set "301 redirect from non-sef to SEF" and "301 redirect from Joomla SEF to sh404SEF" to No under the Advanced tab of sh404SEF configuration.
As for deleting these, I'd suggest to just select that URL from the SEF URL manager and click the Delete with dupl. button which is meant exactly for that. If your server fails at some point in the process of deleting so many duplicates, just reload the page and do it again, until there's no duplicates left.
Best regards
Yannick Gaultier
weeblr.com / @weeblr