Inspect for blockage in the drain tube which carries melt-off from the freezer compartment to the drain pan.
If the drain tube is not blocked, there may be blockage in the drain fitting of the drip tray located below the evaporator coil inside of the freezer compartment. The drip tray will collect melt-off from the evaporator coil while the unit is undergoing each defrost cycle.
With hot, humid weather, additional frost will buildup on the evaporator coil, some of which may form solid ice. Any ice that drops into the drip tray may not fully melt before the defrost cycle ends and cooling resumes. Ice could then block the drip tray's drain fitting and will refreeze with any undrained water when the cooling cycle resumes.
Before dismantling the freezer to access and inspect the drip tray drain, suggest first shutting the refrigerator off and open the freezer door to allow the freezer interior to warm which should melt any residual ice that has accumulated in the drip tray. The door may need to remain open for possibly 2 -3 hours but the process would potentially be accelerated if frozen food is removed and a fan is used to blow warm room air into the freezer compartment.
There is no guaranty ice buildup is blocking the drip pan drain, but it can be a common issue during summer conditions if the freezer door has been open an expended time. If ice is the cause of the issue, warming the freezer will likely have prevented being forced to dismantle and reassemble sections of the freezer compartment or at least the shrouding covering the evaporator fan, coil and drip tray.