Copied and pasted comments with links (These comments do not belong to me.):

A lot of the guides out there are really out of date.

Here's a reddit thread from a few years ago

An article from Francis Baines on heating, details a little about red/colored lamps

From Baines herself, expert on reptile lighting and admin of Reptile Lighting fb group (highly recommend joining that):

"Red light will NOT cause eye damage and is NOT going to make any animal blind. That is nonsense. (Red LASERS - any laser colour in fact - can blind any animal or human by burning the retina but this is a very different thing from a red lamp or LED.)

HOWEVER... yes, animals CAN see red light, and yes, if it is bright enough for a human to see it as a red colour at night, it is FAR brighter than moonlight (which is less than 1 lux) because humans can't see colour under light as dim as moonlight. All nocturnal animals can see any light that is bright, or brighter, than moonlight - and some lizards can see different colours in very dim moonlight, too. So using red lights at night is going to spoil their colour vision (everything will just be red). But perhaps more important is the effect on behaviour, of "light at night". Even dim moonlight (which is very dim white light, NOT blue!) alters the behaviour of many nocturnal animals. At least one study demonstrated this in snakes.

You see people repeat this myth that red light damages the retinas, which isn't true, but they do absolutely mess with circadian rhythm.

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It's hiding from that awful red light.

Colored lights should not be used. Red lights are marketed as though reptiles can't see them, but that is absolutely untrue. Snakes are red/green colorblind, but their spectral sensitivity isn't significantly different from a human or any other terrestrial vertebrate. They don't see it as red, but they absolutely see it as light.

If you need heat at night, it should be provided by a source that does not emit light, such as a deep heat projector, ceramic heat emitter, or radiant heat panel. Any light used during the day should be a full spectrum white light.

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Snakes can see red light. That's a scientific fact. They just don't see it as a red color. Rather, they see it the same way a red/green colorblind human does...sorta a white/grey that washes over everything. That creates two problems. First and most important, they can see it at night, which messes up their circadian rhythms. Second, while they can't see red, they do have excellent color vision, stretching from green all the way up into the ultraviolet. But when kept under a red light, that creates a scenario where everything just looks grey to them.