Something is huge wrong with my training, diet or sleep. Even with very bad form, he'd get that new muscle mass. So we can exclude form or technique right? One person said technique does matter, but how much? 1% or 90%?
Currently I'm also very dissapointed about my life regarding the sport and my body.
I may be coming to the wrong conclusion, but it sounds like you need to develop some context for your efforts. Also need to add it is a lot easier to manage rep and loading ranges using external resistance (weights) - this could be as simple as bags of tubesand or play sand, sacks of pea gravel, rubber mulch, large smooth rocks etc.
My first bit of advice is to read more, Steve recommended an E book, pick it up, pick up some others and read. There are common principles of strength and size training that can be applied across modalities. Second you should join a gym or at least tour the local ones in your area, use any free or discounted trial periods. Pay attention to what's going on in the places where people have impressive physiques. Make a list of exercises you want to use and study video examples until you understand the best form. Do not try to kill yourself when learning form, that comes later.
Push, (pushup variations, incline, decline, one hand, off the knees, dips, dive bombers, Iranian, Dand)
Pull, (pullup and rowing variation - it pays to have suspension gear or at least a pullup bar you can drape a towel over)
Hinge, (Swing, Good Morning, Deadlift variations, single leg deadlift, standing broad jump)
Squat, (Squat, Pistol, Lunge, jumping lunges, step ups, Hack Squats, Sissy Squats, Skater Squats)
The above list is far from complete. Find and learn at least two varieties of each, even if you only wind up using one most of the time.
You need to increase protein consumption, don't just eat more food in general and expect to do anything other than generally get bigger, and with it more fat. More lean protein. This could be as simple as knocking back a can of plain tuna fish in addition to your regular meals. Whey powder is a godsend for increasing protein consumption though it might make you gassy.
For all of your chosen exercises you need to do a light warmup and execute a single set to failure, absolute, gravity wins, failure. Approach this aggressively and honestly. This number of reps sets the loading you will be using and what sorts of mechanical disadvantages you need to apply to keep your rep count in a good zone for muscle growth. You won't need to do this very often, but you will need to pay attention to when you need to add more weight.
The reddit BW RR is not a bad start but really the set and rep counts are meaningless if they don't bring you to the edge of mechanical failure - a point on most of your sets where you are reasonably certain you can't do another clean rep or two. With bodyweight training it can be tricky to manage this, you need to challenge your ability to complete the reps and do it in a rep range under 15-20 at the absolute most per set. A rep range of 6-10 is ideal for size and still give you strength gains to work with. If you are stuck with using higher reps than that, you can still make gains but are going to be out of the best range for building size or strength.
Cluster sets and Rest/Pause are great tools for this type of work when training bodyweight:
Say you can do 12 reps of pushups. You would use about 8 reps, rest 3 easy inhale/exhales = 15 -20 seconds and do another 8, repeat, repeat again. You can use this until you cannot complete 8 anymore, or follow it down until you cannot even get 3-4 reps or until all you can do is slowly lower yourself eccentrically and have to scrape yourself off the floor. Training to this level of failure should only be done on the last set of whatever exercise you are doing, and maybe not more than once per week per exercise. The other 2 sets leading in should still be challenging but limit the effort a bit to blow it in on that last set.
You can also use mechanical drop sets with bodyweight training:
same pushup example of 12 reps max, but this time you go to 12 and immediately switch to pushups done off the knees, again going till you cannot get another clean rep.
In general if your rep count increases into the 12-15 and greater range you need to swap variations or add weight somehow - this goes for all of your exercise movements! Manage the variations of given exercises so you can progressively load yourself, and if using mechanical drop sets have variations ready that you can use to extend your set duration. Drop sets work best if you can restrict the first set to a serious strength range, 3-5 reps or so and then immediately continue with an easier variant to get yourself to 10-15 total reps.
You lifting cadence should be fast on the concentric, slow on the eccentric. Pushups as example, press as fast as you can and maintain good control going up, take 2-3x that time coming down. It doesn't matter if as fatigue sets in you can no longer press yourself up quickly, what is important is that you
try to press quickly and lower slowly right to the last rep.
Once you begin to make some improvement you can seek out more advanced programming, but you need to first establish a base of energetic movement and a gauge of and ability to apply serious effort to your exercises. If you are applying mindful, consistent hard effort, you will see gains - trust the process. You cannot just do a routine of a given number of reps and sets independent of the amount of effort and without progressive overload. For any physical activity the body tries to maintain a survival surplus of effort at which point it encourages you to terminate any further effort. You need to push into this surplus a little to increase the available reserve. If you do not challenge what you are capable of, the body will not invest the resources to increase capacity.
Do not worry about cutting or bulking at this stage. Eat more and if you get fat without adding muscle, eat less. If you develop more muscle tone and don't get bigger, eat more.
You will improve a lot faster in a gym environment training with barbell and surrounded by experienced, motivated people, but it is possible to get there at by yourself at home using bodyweight if you are creative and determined. Again, even at home you will find the going a lot easier with externalresistance - weights of some sort. Many folk tend to think of bodyweight training as basic or foundational but in many respects it is a more advanced form of resistance work than many other options.