Hello! It will be hard to tell exactly what the problem is without proper analysis. But the least I can do is give you some pointers and bump your post in the process.
I’m not experienced with that particular quad but hovering at 80% should indicate a serious problem because I think it should have a lot of punch. There can be a bunch of reasons but the first things I would look for is the things that power the quad. Batteries, battery lead, motors.
What battery are you using, is it charged (check the voltage) have you tried with another battery?
Are all the motors spinning freely when turning them by hand?
Inspect all the wires from the motor to the FC for bad connections.
Inspect the main power lead connection on the FC.
If all seems physically ok you could have a look in betaflight to check your receiver settings.
As you said the word ‘drone’ I take it you are new so please take your props off when you connect the drone to the computer / never plug in battery when connected to the computer with props on!
It is possible your radio settings are not correct e.g. 80% stick does not tell the quad to go all the way up the channel. But let’s not complicate things.
Check the physical things first; battery, connections, motors.