Ok, so there are two things with respect to the database that you want to do;
Verify that your nextcloud/config/config.php is configured to use that database,
Log in to that database via CLI (i.e., mysql -u username -p mydatabase_nextc65) and run SHOW TABLES; to confirm with your own eyes if the table exists. Don’t trust web consoles for the database.
I’m thinking that since it says it exists, it probably does, OR, its in a strange state where it creates it, tries to create it again, fails, and then rolls back (removes it), and you’re probably stuck in database update hell, likely having enabled and then disabled talk at some time in the distant past, and now the migration scripts are failing you.
Probably… what you want to do, is drop all the oc_talk_* tables and then try to enable it. Do yourself a favor though, and back up the database first.
See if they’ll offer you a recent version of MariaDB. Some shared hosting providers will offer a recent version of MariaDB (the true successor to MySQL 5.x) in addition to being stuck with an ancient mysql.