Kelsey-atl

Thank you for responding, @paul2009. I did want to leave a (solved) update here in case someone else runs into the same issue in the future.
Hubspot has a new beta form called the V3 form. This updates the embed code to prevent issues such as the one I was having. Until they are fully released as a permanent solution, I was able to sign up through Hubspot support team to be in the beta user group. Once they activate V3 beta forms in your Hubspot account, you will need to rebuild the form to have a new embed code. If you try to duplicate the form, it will still use V2. 
It looks like Hubspot is making these form updates because of issues like these, so I am happy to see they're already working on it!

I see this on Safari too. At least until the form is clicked, at which point the rest of the form loads.
I don't have a definitive answer but it looks like this could be an issue with the way the HubSpot embed code works. Because the form is at the end of your page, it is not visible when the page loads and so the form may not be able to determine the correct height for the iframe. It would then only show the first part. For troubleshooting, it may help to move the embed to the top of the page to see if the issue persists here. If this is the issue (and it's a stab in the dark) you could try setting a height to the iframe manually.