Bad Interview For A Position I Never Applied For

I think you got extremely lucky and unlucky at the same time. What you managed to achieve is a screening call based on your networking efforts in a fairly relevant company. They told the recruiter something like... this guy is really keen to join us, etc. and the expectation was higher without sending you a proper briefing document or email. You could/should have reached out to the HR team before the interview to set expectations or they needed to provide that setting in a more granular way.

That role is gone, I am afraid. But do go back to the recruitment team you know and explain you are indeed interested in joining the firm, check for other jobs, etc.

just out of interest - how many hours did you prep for the call?

edit: What I noticed is that there a TON of new/graduate recruiters flooding the phone lines with no clue what they are doing. In these cases we, the applicants or clients, need to tell them how to do their job. It is sad but that is the reality of a post Covid employment world. Even HR team members have to start somewhere.