When phpMyAdmin configuration storage is not configured and browser's indexDB is used to store designer pages and coordinates, trying to open a page shows pages from all the dbs. Moreover, this gives an error when you go to the designer of a database whose not the database of the first saved page in indexDB
Fixed with https://github.com/phpmyadmin/phpmyadmin/commit/fdfd9ea89c64880ae47f8572edb3417c12ea5ca3