@clemrivers - one of the things that might be happening, when the user “submits” on the calendly page, it locks in the Calendly meeting but does not yet submit the responses to the questions to the typeform.
if you are not telling your users that there is still one more step to submitting the typeform (and not just the calendly meeting) then you are going to see some drop off
one of the suggestions i would make, based on having this happen earlier for me, is to create two form - one where you collect all the information you want and then the submit function kicks off a redirect upon completion to a new form that is only the calendly question.
this way you would get your responses to your typeform and then the user would lock in their booking in calendly.
just a thought/suggestion
des