Corrupt Confirmation Message After Update

We are currently using v5.7.4 and I have been testing v5.7.5.1 but have run into a problem with the confirmation message on one of the forms.

Prior to the update I see the following message at the top of the form upon submission.

After the update, the message moves to the bottom of the form but the following remnant is left at the top:

What could have changed between these versions that would cause this?

Both forms are almost identical (and I have even tried making them identical) and have the following line at the top:

<p>[response]</p>

If I remove the [response] code then the artifact at the top dissapears but the confirmation message still appears at the bottom.

Please advise.