Needs some work. I assume that 3" line is for a toilet? If so, it shouldn't have a trap under the floor.
The 2 2" traps that connect together under the floor are also not vented properly. You could remove that whole vent line that goes back from the santee note and up the wall. The 2 2" drains could connect separately into the 2" drain line for the lav to wet vent them. Above the lav, the vent could be 1.5"
I assume that the 4" stack coming down is receiving waste from above. If so, it cannot be used as a vent. You need to run a true vent up to the attic (and connect to another vent or run out the roof) or at least 42" above the floor of the highest fixture using that 4" stack. If you cannot run a vent line, an AAV might work. However, they are not approved in all states and have their own problems (mechanical failure, need to be accessible, needs to be able to get fresh air, etc.).