It looks like they don’t have any code that styles this specific part of the list, so the theme’s default css shows up. The code that is being used can be found on line 1699 in the style.css –
.entry-content ul > li {
list-style-type: disc;
}
You can either remove/change that to none or add the override in your custom css section –
.entry-content ul > li {
list-style-type: none;
}
Let me know if that helps