Put a nice coat of mud under the joint tape squeeze it into the joint then put another coat over the top of the tape and feather it out.
Are big gaps in drywall sheets a problem.
The mud will adhere to the drywall fill the joint holding the sheets together and the tape will be embedded inside the coat of mud strengthening the whole joint.
Huge gaps underneath running the length of each seem in all four corners of the room.
The solution is to fill the gaps with patching compound or if they are especially wide with strips of drywall.
The gaps in the joints are even worse where the wall meets the ceiling.
Gaps 1 8 inch or wider between drywall panels can give a drywall installation an amateur appearance but gaps aren t the end of the world.
Filling large gaps in sheetrock gaps 1 8 to 1 4 i usually mesh tape then paper tape.
It looks like the drywall was cut too short in some places the gap is 1 wide and the previous homeowners and or contractor attempted to fill the gaps with mud but it didn t work.
Larger than that i would fill with easy sand 20 in a mud pan.
Once dry shave it and your good to go.
Just fill em up before you get to work taping.
The same procedure works on edges around outside corners that are too uneven to.
If you have smaller gaps in butts and flats mesh 1st then paper tape.