At 6' most cable should work with Blu-Ray if it were direct to the TV. Make sure you get certified High Speed cables (the packaging should specifically say "High Speed"). The cable manufacturer should say the cable is certified or at least there should be a large number of reviews with happy customers. A 6' certified High Speed cable should not cost you over $10. If it is over $10, look elsewhere.
Based on your original append, I think you're missing an important point. It was acting up all of these years. You were on the edge of it being worse. When you changed components you went over the edge. You have the same problem you always did, it's just the symptom got worse.
The good part about that is that if you disable Deep Color in both the Blu-Ray player and the TV, you'll likely push yourself away from the edge that the symptom *may* go away.
BTW, welcome to the AVSForum. You'll find that your Blu-Ray player model and your TV model have specific threads in different parts of the AVSForum. The archives are extensive and worth reading to find out causes of issues or the proper starting settings for TVs.