Correct and would like to add none of these POE Splitters are formally rated for outdoor use. Meaning they offer no specifications as to how they operate in extreme heat never mind damp locations.
These are active splitters and incorporate some electronics and passive components. I used them to help convert the bulk of my (IoT) devices to POE so everything was home run, properly surge protected, and powered by my UPS systems.
It helped remove lots of wall wart PSU’s!
I would suggest you test one unit to see how it performs before going all in. For those wanting to extend the service life of the unit just break it open and mount heat transfer tape to the camera JB enclosure so the entire box acts like a radiator.
If no enclosure is used and the unit will reside in the attic (don’t recommend this) insure it’s secured in free air to allow heat dissipation.
If the OP lives in any of hot zones like AZ, TX, NV, etc don’t expect a very long service life in the attic besides this being a fire code violation!