The option of embedding a Hubspot form as @karstenkoehler suggests would be a good step forward for you, but it may not solve the problem entirely. Hubspot recently enabled a new feature for phone number validation and formatting, which is likely the source of your frustration.
After digging through existing Knowledge Base articles and blog posts to find any information on the update/change to automatic phone number formatting and validation directly from Hubspot, I found…pretty much nothing.
So, I created a new Idea that encapsulates the feedback of not only your post here, but much of the other feedback and comments that I have come across in my search for info on phone number validation and auto-formatting. You can find that new Idea here.
Knowing that Hubspot only makes feature requests when a sufficient number of users request it, I would recommend upvoting and commenting as many of these ideas and posts as possible. The others I found are here, here, here, and here.