No one cares about grades in the real world so having one on your academic record will not carry-over into employment.  A bad project in your portfolio certainly will have an impact tho, but at least you get to choose what you show or exclude.  If you're already in a M.arch program, then it's not that big of problem since you've already made the cut but it will impact scholarships.

Some folks recovered from a poor first project to become stellar students. They learned from their mistakes - usually time management - and improved their representation, spatial thinking, and ability to execute. Some others found out that they were not made to be architects after all - admissions had made a mistake recruiting them and their inability to think in 3D and poor aesthetic sensibility led to the decision to leave the program after a couple of semesters. They all went on to successful careers that leveraged their (non-design) skillsets.

I did not due well in my first design studio.  I learned from my mistakes and have succeeded in doing well in my subsequent studios.

i was a pretty bad student in general, esp in studio.  undergrad gpa was under 3.0. Grad school was much better,(3.7ish)

I firmly believe that grades are a pretty poor indicator of future success/failure 

Not a big deal.  There is plenty of time left in your academic career to address whatever issues caused your low grade.  You are in school to learn and develop skills.  Get to work on that.   So what if you aren't great right out of the gate?  Maybe you are out of the running for whatever your school gives to the top students at graduation, but you are still going to get a degree.   When my old bosses would slobber over job candidates from prestige schools, nobody mentioned or cared if they were in the top or bottom of the class.

Barring a major economic shift between now and May, you shouldn't have a problem finding an internship this summer.  Few, if any, potential summer employers will ask about your grades, they will want to see a portfolio and perhaps some computer skills.   Work on strengthening your portfolio if the look of your last project was part of the problem. 

I got a B+ in studio and was beating myself up over it...then I realized it doesn’t matter.

Just forget about it and move on.

Employers care more about your portfolio and your personality. I have yet to hear of an employer asking for a transcript. Try to learn from this semester and improve next semester. Honestly there's nothing to be stressed about. However, you want to do what you can to have a strong portfolio and be able to thoughtfully talk about your projects when pursuing entry-level professional work.

Check these out for some context if you'd like:

The Secret Nature of the Job Interview

Understanding Architecture Internships

Better Critics Than Crickets: Thoughts on Criticism and the Willingness to Be Teachable

It's possible that it might matter if the pattern continues, depending upon how your school decides to handle the issue. Talk to your professors and try to get feedback on your mistakes which you can act upon.

Considering the same project can be a D at one school and an A at another, does it really matter? Growth mindset is all that really matters.