There is a lot of good info in these posts, but I do not think that buck fever and target panic are the same thing. Yet, it is entirely possible that an archer could have both and that one could contribute to the other. Being a stone cold killer with a rifle does not translate to the same with a bow for many reasons. What makes target panic different, IMO, is
inability to execute a shot sequence correctly.
Every archer has a shot sequence, but it is not the same for all shooters and may differ for compound shooters and trad archers (I have done both). I bet few bowhunters could execute a shot sequence exactly like the best Olympic gold metalist, but you do not have to. Nor do you have to change everything up and do what your best friend does, or even the best on-line expert. However, I do think that the basic fundamentals of a shot sequence must be learned and must be repeatable. Here is my take on them: 1) draw to a consistent anchor, 2) aim, 3) have a decent release. Shooting a gun or a crossbow, effectively takes care of #1, but you still have to do 2 and 3 well to kill deer even with these weapons. Failing to aim or flinching with a scoped rifle still results in a bad shot.
What makes target panic so difficult for some to overcome is that it is both mental and physical. Your normal/best shot sequence is harder to master when under pressure (the buck is broadside at 20 yards), and that part is often mental. However, humans are creatures of habit, and if you learn bad habits, like short drawing or not aiming, they can become ingrained. In fact, they become physical, biological. Everything we do is dependent upon nerve pathways, and with target panic the normal shot sequence pathway, where everything goes right, gets neurologically by-passed, so instead of doing 1, 2, 3 your nerve pathways change to 1,3 for instance. One miss one time is not necessarily target panic. However, target panic is really ingrained, repeated (bad) habits often associated with elevated pressure (internal or external) that result in neuropathways that short circuit your ideal shot sequence.
When I was trying to shoot trad instinctively, I could draw my bow to a comfortable anchor with no problem, unless I was really trying to shoot (internal pressure) and then I would regularly short draw. Just the common advice of "burn a hole in that target where you want to hit it" created enough pressure to throw me off my shot sequence. Other people can hit anchor solidly but forget to aim. Others can't get a good release and flinch or yank the string back upon release.
A good "coach" can help diagnose such problems, but only if you are doing it when they are watching. So if you are rock solid on targets and only struggle on deer, a coach on your target range may not be much help. However, I doubt that anyone can properly diagnose your problem from your posts. Target panic generally is associated with elevated pressure, but having a coach watch you shoot may be enough to create such pressure.
The most important thing that I can really say, however, is that target panic, if you really have it, is not just mental. Many well meaning friends will give you advice as if you can just fix it with X or Y, but it is not that easy because you have ingrained neuropathways that are not achieving the desired results. Think of it as a computer, if a hacker puts a "bug" in your operating system and it fails to boot properly, turning it off and then back on, or rearranging your set-up, or even replacing your monitor is not going to help. You must reprogram the operating system. It is the same with target panic, in order to overcome faulty, ingrained neuropathways, you have to ingrain better neuropathways so well that you don't slip back into bad habits when under pressure. This is where changes to your shot sequence can help, like shooting the cards (affecting aiming) or a clicker (for anchor).
I agree that there is some great information here and elsewhere on the internet, but if you really have target panic, it may be a slow path to overcome it. And, anyone who recommends a quick fix may have no freaking idea of how to solve your problems. I believe that you can self-coach yourself out of it, but garbage in, garbage out. Make sure that you are putting the right stuff in from a skilled and qualified "coach," and not just grasping for whatever "some guy" who appoints himself an expert says. This said, however, I do think that you can learn some things that will help your manage the pressure (mental side) and good techniques for dealing with the repeatable shot sequence and neuro pathways.
Personally, I do not consider myself an expert and won't offer a lot of specific advice, but I did rely on stuff from Jay Kidwell when I was struggling with target panic. (see
https://archivalarchery.org/Documents/TargetPanic/TargPan.html) It really helped me, however, to understand why I was having such a hard time fixing my problems. But, I do think it would be helpful for you to separate buck fever from target panic. You may only suffer from buck fever, and that may be much easier to fix. Good luck. - Hugh