I use code blocks quite a bit and unfortunately Deepdwn is the only application I use that converts special characters (e.g. > or &) into their codes (eg > or &) when copying and pasting from some other applications (e.g. Slack, or Jira, or a browser). I have to remember to paste the code into something like Notepad/Notepad++ first, and then into Deepdwn, and then it works.
For example, if you copy a line featuring redirect operators (> < etc) from here: https://www.gnu.org/software/bash/manual/html_node/Redirections.html straight into Deepdwn, it comes out like this:
"If >&- or <&- is preceded by {varname}"
becomes
"If >&- or <&- is preceded
by {varname},"
So you can see the conversion. Note that it happens inside and outside of code blocks. Also it's adding linebreaks where it shouldn't, but I've only just noticed that, so not sure how consistent or related that is.