What are the reasons for a very heavy clutch?

[MacBryce]

The reasons for a very heavy clutch are: 1. Mechanical issues in the clutch operating mechanism causing jamming; 2. Insufficient or leaking hydraulic fluid in the clutch master cylinder; 3. Rusting of the clutch slave cylinder; 4. Blocked air passage or air leakage in the clutch booster cylinder; 5. Broken or bent clutch release fork; 6. Detachment of the release bearing or bearing seat. The clutch is installed between the engine and the transmission, serving as the assembly component in the vehicle's drivetrain that directly connects to the engine. The clutch is mounted together with the engine crankshaft's flywheel assembly and acts as the component that cuts off and transmits power between the engine and the vehicle's drivetrain. Throughout the process from starting to normal driving, the driver can operate the clutch as needed to temporarily separate or gradually engage the engine and the drivetrain.