Here's a technique to prevent marker armor stands from turning black

Everyone is familiar with the biggest conundrum of armor stands. If they have Marker set to true, they're uninteractible and easy to use as, well, markers, but their origin is set at their feet.

If you set Marker to false, the origin is a bit more manageable, but it now has a hitbox and a bunch of other issues that might interfere with your project.

When rendering items, it would be theoretically best to use a Marker armor stand, but in practice it's difficult because they turn dark when too low: https://i.imgur.com/MdKyDvA.png^[1]

However, I have found a solution (albeit a bit of a wonky one). If the armor stand is set on fire (using the Fire tag), it will display in full light, even if it's Marker and inside a block. To make matters better, it does not display the fire that it normally would if it does have Marker set to true. Here's a picture of this: https://i.imgur.com/ubA6gZ5.png^[2]

Unfortunately, the max time an entity can be on fire is only 27 minutes, so a clock would be necessary to reapply the fire. But other than that, I think it's a pretty neat solution! Thanks to ZedFalcon for indirectly inspiring me to test it.

TL;DR: Marker armor stands on Fire aren't black when they're inside a block, and don't display the fire texture either.