CFDB Plugin

The WP-SpamShield plugin injects into your form submissions an additional column with random hexadecimal names. Examples:

https://wordpress.org/support/topic/many-extra-columns-being-generated-with-long-string-random-names/

Solution: CFDB Options page, Saving tab, Do not save fields in DB named (comma-separated list, no spaces) put this:
/.*wpcf7.*/,_wpnonce,/^[a-f0-9]{32}$/