Your streaming box was either not configured properly, or was very low cost.
The most likely solution is that you need to turn on a feature on your streaming box that sets the output refresh rate to match that of the content you are playing. On Apple TVs it is called “match frame rate”. I know Rokus and Android TV devices have similar options.
Newer TVs can detect when 24 fps content is being delivered in a 60 hz signal and render it to the panel correctly, but this doesn’t usually work if you have the selected input set to any low-latency modes (“Game”, “PC”, etc)