How is this even acceptable on a watch that we are supposed to wear pretty much 24/7?

Sorry you're experiencing this. I haven't has anything like this happen with any watch. 

I have made my research, more expensive watches with that sensor do not have plastic housing and it does not penetrate the skin, elevate 4 sensor is made of smooth plastic without the housing so there isn't a gap in between the glass and the plastic. I think this particular line of Venu 3 is just poorly designed and I do hope that Garmin will actually look into it. If you look on Amazon it has a disclaimer that it is a frequently returned item. 

For me the marks are normal but it doesn't cause any pain at all. I'd assume that the elevation is there to make sure that it doesn't slip around and therefore get a better hr reading.

My advice would be to take it off frequently (e.g. during and after shower) and let your skin recover before putting it back on. I'm also using a 3rd party nylon band with a velcro fastener so I can control the tightness to my liking.

In addition to what tso123 mentioned, I would also switch wrists. I usually will wear my watch on the left wrist during the day, then on my right wrist during the night.

I would agree with what "tso123" said. I do have the marks on my wrist after wearing Venu 3. I also agree that the Venu 3's sensor protrudes out a little compared to my old Vivoactive 3. But in my 7 years of using Garmin, it has never caused me any discomfort and I remove my watch everyday during shower. I don't change the wrist during sleep, but that is something you can try. The only time I wear my watch tight is during any activity recording. Also, I use Garmin's Nylon band and that really helps in terms of comfort. 

Are you feeling any discomfort around the mark area? If yes, you need to swap wrists frequently and probably apply moisturizer or something. I would not recommend moisturizer and watch on the same wrist. Apply moisturizer on one wrist and change the watch to another, maybe during sleep. Also, I cannot say clearly from the photo if your skin is dry, because this can be a problem if your skin is dry, and swapping wrists is recommended for such people.

switching hands meaning I will have to go into the app and switch the hand I wear my watch on and it simply just cuts into my skin, if I wear it any more loose it will wobble and hang down on my wrist. I understand you’ve wore Garmin for 7 years but Venu 3 is a rather new watch and the only watch with that sensor in a plastic nest, I truly believe that it is poorly designed. You can see the gaps in  between the plastic and the sensor and that is what cuts into my skin.

Do you wear venu 3 or a different watch? 

the gaps look a little different when taken from this close. Maybe you can approach Garmin for a replacement unit. You use the word 'Cut' rather than make an impression or mark. They convey a different meaning. I guess contact Garmin for a replacement unit to see if that helps.