Home World Approval Lower than other planets?

It hasn't reached it's population cap.

Even if it isn't at its cap, is it still more than your other worlds?

you need more moral bouldings on home planet than other planets

I almost always put the Political Capital on my homeworld, partly for that very reason.

you probably crossed one of the thresholds where morale becomes significantly worse due to population. a secret police center might help a bit. if nothing else works, tear down farms.

At least in DA, my testing of the Secret Police Center suggests that it doesn't work. It's not boosting the base morale.

What about the Counter-Espionage Center? You tried putting that on your homeworld?

All other things being equal, the homeworld has a higher population capacity and therefore will have much bigger morale problems than other planets. Build just one farm on your homeworld and you should be fine.

I try to stay away from the secret police center since it can't be decommisioned later. And I noticed no real morale change once it's built. What I am attempting to do now is create a super capacity colony ship and just send them out into space somewhere. All the habitable planets are taken. Hopefully a severe enough drop in the population will provide a short term solution. I will try destroying farms as a more permanent answer.

try to stay away from the secret police center since it can't be decommisioned later. And I noticed no real morale change once it's built. What I am attempting to do now is create a super capacity colony ship and just send them out into space somewhere. All the habitable planets are taken. Hopefully a severe enough drop in the population will provide a short term solution. I will try destroying farms as a more permanent answer.

Why not make a super capacity troop transport instead ?
You could use it for invasion or add it to another planet's population if you wanted.