@d0ublezer0, i verified about Joomla $db->insertObject the save way to add records in the DB.
The only they do is use $db->quote($vallue);
db->quote without 2nd parameter escape the string, so in the DB all are right inserted(you have no backslash in the table).
I tried allready to inject queries inside on insert or update, this get never executed, only in very old servers, you can have the problem, but then not only for mysql queries. So i really dont understand why they have added encoding, the problem was not on insert in the field, but on display only.
Because an input need to have double quotes, you have to use htmlentities($str,ENT_QUOTES,'UTF-8').
Note that since PHP 5.6 ihtmlentities use always UTF-8, but Joomla 4 want only php7 support, so this UTF-8 is only for compatibility and is obsolete for Joomla 4.