I think the green cursors are from when you were editing the code and then deleted tab. repl.it probably thought you were still in. Hopefully, repl.it will fix it soon.
Have you tried refreshing? Logging out and back in? Does it do this with other repls? If not, you can just fork the repl.
I have tried:
(1) Refreshing the repl
(2) Logging out and back in to edit the repl
(3) Using another browser : Firefox
(4) Fork the repl
(5) Adding a new repl and key in the same code
(6) Adding a new repl and key in different code
(7) Logging different accounts and key in the same code
The strange color( green or red somtimes) cursors always appear
while I try to edit my code.