After updating my linux system I found that when I went to do a mouse-paste in VIM that instead of just interpreting the characters, it went right into insert mode. This is a problem when I want to paste in a bunch of vim commands, which can be helpful if you need to re-do a series of actions multiple times.
It turns out the fix has to do with “xterm-bracketed-paste” and I had to put this in the .vimrc:
set t_BE=
I hope this helps someone who got surprised by vim version 8 functionality!