I think this is a necessary feature for forms in general. Forms should allow us to change the text input color and the background color of the input field.
to be able to change color from the light green/blue is a must, or Hub spot just do a change the color in the APP , more contrast to the background, it is to low. Contrast probably ok when you are 20 y but not when you are older.
I can't believe HubSpot doesn't allow you to change the color of field inputs on a form. Ridiculous! +1 for this...or I might just give up on HubSpot alltogether.
It's a real bottleneck. We use slide-in HubSpot forms on our external WordPress website. However, because these forms were generated using iframe, we can't change the input colour even by custom CSS changes on the website. So, it's a dead end for us.