This is not a venting problem. You have a possible blockage. Get a plumber to check your sewer lines. They may need to be cleaned out.
Clear the stoppage in the line that is causing things to gurgle.
A tub drain vents through the overflow.
NO way
maybe bcuz to save water..
I will usually pick the toilet straight up and set it in the tub if there is one. Put a towel in first to protect the tub finish and then tip it front to back several times to cause the water to come out. You can set the toilet into a pan big enough to hold the bottom and then carry it outside or rock in in the pan. There is only about a gallon at most in the base of the toilet after you have flushed it.
The clog is below the point where the toilet and the tub join the drain.
15 inches from outside edge of tub to center of toilet flange.
think the drain may be slightly blocked. Your best bet is to call a plumber now to fix it. If you leave it too long you may have toilet water coming up in other areas in your house. You can try to fix it yourself but most of the chemical treatments don't do a lot.
A bathroom would have a toilet-sink-tub and or shower. A half bath has a toilet maybe a sink but no tub or shower.
People go in a tub then the tub empties it into the air.
The drain is plugged between the tub and the sewer or septic or in the case of the septic system, the tank may be full. The toilet had to go somewhere and the tub was available.
The tub and toilet connect to the same drain at some point. The main drain was plugged but the connection between the toilet and tub was still open. Water seeks it's own level. When the water came up in the toilet, the tub was lower so some of it went there.
You have to use toilet more
A mainline stoppage.