Attaching a lead to a Strider in lava then flying away, will make the Strider flip flop to being cold and warm in a repeating pattern.

In creative mode, if you attach a lead to a strider when it's in lava, then fly away fast, then the Strider will flash from being cold to warm in a repeating pattern, unless you stop, or the lead breaks.

Since it's in lava it should stay warm, but it doesn't