The bug
Despite being cold outside of lava, spawning in lava, and just generally move much faster in lava, striders always tend to leave the lava behind, especially in the overworld, and just walk out and leave the lava.
Easy to recreate, just make a pool of lava in the overworld and spawn a strider in it. The strider will leave the lava quickly and walk off, seemingly not caring about the one thing that will warm them up.
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They also never try to get back into lava.
this bug also seems to include the fact that zombie piglins can spawn using a strider egg