In case anyone else wonders about this, I've compared the formatting in v10 with the one in v12. The formatting in v10 was generic (not aware of the schema or the specific type of XML document) and was considered intrusive because it inserted indents between tags that previously did not have any space and this could result into a significant change for the XML. This behavior was changed in v12 with the introduction of the schema aware format and indent.
If you'd rather use the old type of XML formatting from version 10, you can disable the option "Schema aware format and indent" from Options > Preferences, Editor > Format > XML. This will affect all types of XML files, not just HTML.
The file(s) should be reopened for the new settings to become active.