I know what is tries to do: show a highlight of the the inserted text but more often than not it just doesn´t work and I end up manually cleaning the debis away.
Can this feature be disabled?
Have you tried pasting on terminal control shift v?
That happens when you type the quote character then do the paste.
By default the quote character is ctrl-v, ctrl-v is not paste in a terminal.
You can reconfigure the keys in the terminal app and your .bash_profile if you want to avoid this. But at the cost of using non-standard keys.
You can see what the default keys are with stty -a, lnext is the quote character.