The SubmitButtonElementBlock.ascx in version 4.28.0.0 renders the class attribute twice which causes problems with the styling of this element:
<button id="7e374cd6-a2e7-47f4-a9c1-35cf941ef307" class="" name="submit" type="submit" value="7e374cd6-a2e7-47f4-a9c1-35cf941ef307" data-f-is-finalized="false"
data-f-is-progressive-submit="true" data-f-type="submitbutton" data-f-element-name="__field_10047"
class="Form__Element FormExcludeDataRebind FormSubmitButton">
Submit</button>How can I submit this as a bug?