I am confused by this conversation you folks are having. My understanding is that Heroku has nothing to do with this. They are correctly using ISRG Root X1 lets

I am confused by this conversation you folks are having. My understanding is that Heroku has nothing to do with this. They are correctly using ISRG Root X1 letsencrypt certificates. It is the client's computer that is incorrectly using the old DST Root CA X3 certificate because they have an outdated certificate store. Please correct me if I am wrong.