Reduce Complexity - The less shit you do, the better you are going to get at the things you are doing. The best squatters usually squat a lot. The best deadlifters usually pull a lot, and the best benchers usually bench a lot. The rest of their shit is usually irrelevant. I have no idea what Konstantinovs can overhead press because everytime I see a video of him he's deadlifting and benching. And guess what? He's pretty fucking good at those things.
It's pretty simple, if you want to get really fucking good at a lift, do that lift.
The same holds true with eating. I still see people arguing over keto, paleo, IF, CBL, and everything else. While I enjoy trying new diets out, when/if I do a bodybuilding show I will do a very simplistic bodybuilding style diet. And you know why? Because that shit works, and has for decades and decades.
Anytime you find yourself stuck in a fucking rut, eliminate as much bullshit from your training as possible and you'll find yourself moving weight and making progress again.
Narrow down your big movements to the ones you can move the most weight on, that you can do injury free. Throw in a handful of small movements to round it all out.
As far as eating goes, eat good quality food, get quality protein in, lots of vegetables, and clean complex carbs.
If you want to shed bodyfat, just keep the above going and reduce calories where needed.
It really is that simple.
Moving weight vs making muscles work - This is something that you can really only learn over time, but there is a total difference in making muscle work, and moving weight through space.
If you haven't been paying attention, in small workouts you should REALLY be trying to make the muscular area work. If I had to make a list of movements where you are just moving weight through space.....
Squats, Deadlifts, Bench, Overhead Pressing of any kind, Incline, lunges.
Making muscles work.....
Side laterals, face pulls, curls, tricep work, lat pulldowns, rows, shrugs, uptight rows, leg curls, leg ext, flyes.
Neither are all inclusive lists, it's just an idea of how movements should be used. And some of these can even be swapped out. For example one could use the bench press to make his pecs work, however switching over to a machine or db's for that would work even better.
Use the right tools for the job. The lat pulldown machine shouldn't be used to lean forward and then rock back so you can get the weight stack moving. You should use it to work your lats. Same for rows. Why the fuck are you doing a sloppy as shit row? Aren't you just trying to hit your rhomboids? Well you may or may not be doing that when you monkey fuck the bar up, rather than pull it into you and squeeze your back together.
People may not know this, but I will give this little secret. You can get big as fuck doing that. Just a little FYI there. Learning how to make a muscle work will also help you if/when it comes to rehab something. Trust me. It behooves you to learn the difference in these two techniques. Yes it takes some time, but if you put an effort into learning that with the right movements, it will pay big dividends.
Apply these two principles to your current training paradigm and see if it doesn't help you tremendously.