Hey Oleh D. , given you're using Zerobounce as the validaton step, just keep in mind that it doesn't support validating catch-all emails so every catch-all email will be marked as ""invalid"", even though they're not truely invalid, Zerobounce is just unable to validate them (which is different)
Switching to an email validation provider like Findymail in the waterfall settings can help getting more coverage for those cases too (as it supports catch-all validation)