Hi! I follow a scene referred workflow, but I’m entirely dependent on the LUT 3D module (which is at its recommended position between “output color profile” and “sigmoid”).
The manual for the dated version 3.6 lists “recommended modules”, “modules to be used with care” and “modules to avoid”. LUT 3D is nowhere to be found in these lists.
Is this list still applicable in 4.0? Is LUT 3D recommended or not?
Do you get satisfactory (for you) results?
Are there any nasty artifacts after applying the LUT?
If answers are “yes” and “no” (hopefully in that order 
), why not use it?
For all the modules with a warning against them, the reason for the warning is given. Quite often, it is either because newer modules provide a better/easier alternative, or they work in Lab space, with associated high risk of image artifacts (haloing, in many cases). So, except for the few modules that are actively deprecated, you can still used them, at your own risk.
The LUT3D module probably isn’t mentioned because the major objections aren’t valid, and if it’s needed, there’s no real alternative.
3D LUT is display referred, but there isn’t another module like it in the scene referred part of the pipe. As long ad you’re aware of the limitations and don’t push it too hard, you’re fine.
There is a lot of great info that might provide context of the implication’s of using a certain LUT and for a certain purpose …where that might be located etc etc… I guess knowing what your LUT does would be the most key things so that you can predict what it will do when you insert it…
I found these 2 links very good to help break down some of the nuances of using LUTS…