"Transmission overheating, slow down". Should I do a flush/refill or just drain?

What is your question?

At 60,000 miles, a local mechanic changed my transmission oil for me, I believe it was Valvoline brand, and ever since then, I've been getting the overheating message while I drive at highway speeds. My car goes into limp mode and makes a whining noise when I step on the gas, so I need to pull over for 10 minutes and let it cool down. I am going to get the ENEOS CVT fluid this time around and change the transmission oil to see if it helps. Would you recommend a flush or just to have it drained and refilled?

What makes this problem better or worse?

Slowing down or stopping to let the transmission cool down

How long has your 2015 Mitsubishi Outlander Sport had this problem?

A month