Since you've already tried the standard driver/update fixes, a few things worth trying if you haven't:
Settings > Devices > Touchpad > scroll down > Reset — resets the touchpad driver config back to defaults specifically.
UEFI test:
Shut down the Surface.
Press and hold Volume Up, then press the Power button.
Release Power when the Surface logo appears but continue holding Volume Up until the UEFI menu opens.
Try using the touchpad there.
If the clicking is still intermittent in UEFI, it's likely a hardware issue.
If it works perfectly in UEFI, Windows, drivers, or software are more likely responsible.
Safe Mode test — if it works reliably in Safe Mode, a third-party app or background service is interfering.
If none of that helps, a full Surface Diagnostic Toolkit run or reimage via USB Recovery Image is the next escalation before hardware service.