You've been drinking more?
Seriously, probably a sensor, but could also be a small run in the toilet.
there is a foreign object caught (cell phone ,kid toy,tp holder ,etc,etc)
your dads
Normally 3" BUT if your using a sewerage ejector you can go with a 2" grinder pump if properly vented
Gravity
on average of average people it would be 4.5 flushes per day (poor toilet)
My g/f has this happen to her regularly and, it was only when I asked that she said she usually flushes once to get the flush working and then immediately after to make certain the toilet flushes everything away. She said that if a toilet has good pressure, it will often splash out when she flushes.
Many toliets are designed to save water so for some "jobs" it takes two flushes.
No less then 3" unless your using a sewerage ejector
The main toilet pipe is partly plugged after where the upper pipe joins the lower one.
School prank- Putting someones head in a toilet, then flushing.
Check the flapper and re-adjust the fill height.
u dont flush the tolet