[Bluepill]

Probably the top 2 suspects:

1. Due to normal wear on the compressor clutch, the gap has increased. When the system runs for awhile and the clutch and its electrical coil heat up, there is no longer enough magnetic power to hold the clutch engaged. You can run it at road RPM (2500-3000) for awhile at rest with the hood open and watch the clutch. You can also use a feeler gauge between the clutch plates and see if exceeds spec.

2. If the air flow in the system is restricted (always run with all vents open and a clean cabin filter) or the evaporator thermostat is out of spec, the system can overcool and cause the water that condenses in the evaporator to freeze and block airflow. With the decreased airflow, cooling is reduced.

3. Check youtube for videos. As always, there is a lot of BS out there, but if you sift through it you will probably find some decent info.