If it is helpful,
The knitting problem came up after I have attempted to install tinytex using:
tinytex::install_tinytex(repository = "http://mirrors.tuna.tsinghua.edu.cn/CTAN/",
version = "latest")
because I had the same issue about Certificate being out of date mentioned in this post
Upon installation I saw this Warning message:
In file.remove(exist_files(c(dir1, dir2))) :
cannot remove file '/Users/rachelyan/Library/TinyTeX', reason 'No such file or directory'
This is everything I could think of that may lead to the issue