Invalid CSRF token

When I visit a web site and try to login, I'm getting a message that states, "Invalid CSRF token", and the site won't log me in. I've tried Google and Wikipedia about this and while they give info, that info is way beyond my computer knowledge.

I have determined it seems to be something that has attached itself to my particular input through my Safari app. If I use a different browser, Firefox in this instance, the problem does not happen.

This laptop is a MBP (Retina. 15-inch, Mid 2015), macOS 10.14.4

I also have a MacBook (Retina, 12-inch, Early 2016), macOS10.14.3 that does not have this problem

My next step is to re-install system software but I wanted to get some feedback before I go there.

Does anyone know about this?