Why does my iMac keyboard go "connection lost" then "connected" all day?

It is so awful for the last week to have this green light blinking on the keyboard and the monitor to say, “connection lost” then you can’t type; then “connected.” Or the last letter typed (like “e”) will go , “eeeeeeeeeeeeeeeeeeeee…” Can doing “updates” cause this? How can I fix it? TIA !