https://www.saversplanet.com/color-mix-screensaver/ There are several nice ones - no ads or signup. Try Color Mix, Calm Sky or Midnight.
I haven't used a screen saver in years. My laptop just goes to sleep after 5 minutes of inactivity (black screen.)
My laptop does not time out or sleep. I have a desktop background, but not a screen saver. I think those came about in the old days of CRT monitors so you wouldn't get an image burned into the monitor.