My new construction home is losing water level in toilet bowl after flushing, out of three baths two toilets are doing this?

Sounds as though there either is not a vent pipe, or the vent pipe is obstructed, causing the water going down the pipe (like after a flush) to create a siphon effect, thus pulling the water out of the bowl. This assumes that after a flush, it continues to make a "glug glug" sound a few times after the flush cycle has completed?

Sounds as though there either is not a vent pipe, or the vent pipe is obstructed, causing the water going down the pipe (like after a flush) to create a siphon effect, thus pulling the water out of the bowl. This assumes that after a flush, it continues to make a "glug glug" sound a few times after the flush cycle has completed?

Actually the water is going down after the tank and bowl have refilled. Afetr no use the level drops?

If this is a slow and gradual drop in bowl water level, not use-specific, then it leads me to another question. Does the water level seem to surge up and down? Does it happen all the time, or does it only seem to happen when it's windy outside? If so, then the wind passing over the vent pipe (on roof) could be creating a suction and pressure effect. Does the vent pipe have a rain cap on it or is it a strait, open pipe?

Do all three toilets in your home get regular use, or just one? If so, then is it the other two 'unused' bowls having this problem and not the normally used one? It could be evaporation from the unused bowls if this is the case. Unlikely, but I've seen it. This is assuming it's a slow process, over a few days. There are many variables to this issue, lol.

Since this is a new home, I think the plumber should be looking into this for you. But anyway here is my opinion. I think it is very possible that you have what is called a "Sand Hole" in the molding of your commodes, this happens sometime when new commodes are made, most of the time they are noticed in testing and repaired while at the factory.

These holes are not in a place that the water would leak onto the floor but in a place that would make the water go directly down the drain. If you found the leak it could be repaired with an epoxy but I would rather see you get a new commode under warranty if that is the problem.