Trouble with Zero Bounce? Validated Emails Not Matching Up?

Is anyone having troubles with Zero Bounce by any chance? I use Debounce as my default validation tool for work email waterfalls, and then run all of the validated emails with Zero Bounce. But I've got a table of 1.3k people where 446 of them had valid emails according to Debounce, but only 28 of those were considered valid by Zero Bounce. This proportion is a lot smaller than normal, so I thought it would be good to check.