I've been having shinyapps.io performance issues for the last several days as well. My students are reporting that the app (a learnr tutorial deployed on my Shiny account) either fails to load, or works initially but then starts hanging at some point. This is the case even when they don't execute any code in the app, other than to answer multiple choice questions.
Like you, I also had subsequent deployment issues (from RStudio Cloud to shinyapps.io) - the issues were with deploying a different app though, not with redeploying the same problematic app. Not sure if it's related. I got the 409 error but apparently that may be because I was replacing an older version of the app with the same name.
Hard for me to say if the performance issues lie just with the one particular app, or with my other apps too, since my students only work on one app each week.