Copy/paste your actual workflow into the post. It’s unlikely anyone will be able to guess what is wrong from screenshots. I’ll try to guess anyway and say you have some mismatched expressions/field-names in your GMail - Send a message node, or maybe you forgot to switch some of the fields from fixed to expression.
Another guess is that your expressions in the GMail - send a message node reference $json.something which would be the output from the Sheets - append (i.e. first-previous) node, which would be reduced to only the fields that were added to a row in the sheet. If so, you might need to change those expressions to $('Edit Fields').item.json.something to “reach back” to the fields/data you had before the Sheets step.