Every time I visit a user's record the 'contact info' page shows the name of the same user (a 'super user' though I've now set him to registered)- not the correct one;
the address fields and subscription details remain unchanged and the correct name appears very briefly before being overwritten with the offending name, username, email (and Password?);
the site is still joomla 3.9.28 and CB is 2.6.4+build.2022.01.04.22.00.38.045bcf7e0