Whats the appeal of thumbless.. so you can end up in a youtube video lol?

I am going off memory and opinion but I remember this video of a doctor showing our forearms and hands. We have all these little long band looking things. I think he called them flexors or extensors I dunno Im sure theres a ton of crap in google. My point is though lets say I take 315 lbs pick it up dump it on the rack and let go real quick. I can feel whatever this extensor thing is jump in my hand / wrist area. My bodys way of saying "don't do that!". I'm a big believer in controlling the weight from start to finish. Not saying thats what happened here, but I know I have been guilty of getting in a hurry and letting the weight go too quick or grabbing it and lifting without getting my hand perfectly tight and positioned.
What you are describing I call a tweak. My left knee is clicky but rarely gives pain. My left elbow is prone to tendonitis occasionally. My right shoulder is clicky and coming back from a rotator cuff tear. You have to change the hand position if the thumb is messing up. Find a way. Try some different things.
I have a buddy who decided to "work through the pain" on barbell curls. His barbell curl is pretty wicked. I told him knock that s off. He first complained about a right bicep tenderness/pain in the tendon a month ago. Keeps doing them - its getting worse. Finally I told him you've got to stop man I know you are sick on this exercise but do something else. Do dumbbell curls or dumbbell hammer curls and get beast on them.
I had to give up T bar rows because they trigger my tendonitis. Lately been doing dumbbell rows and bent over barbell rows no problems.