I think this is a very broad question as injuries resulting from bodybuilding or strength based exercise can range wildly depending on the intensity that someone does. The typical person that's just trying to stay fit and strong is going to have a wildly different experience and train in a wildly different manner than someone trying to get their IFBB pro card.
Barring any freak accidents, most injuries that result from resistance training are overuse injuries. The most common and prolific being DOMs (Delayed Onset Muscle Soreness) which can range from mild annoyance to debilitating. Even at its worst, it will recover in about a week. Another common, more severe instances would be muscle strain (pulled muscle) and pulled or torn ligaments and tendons. These require a lot longer time to recover and usually require you to stop training entirely until healed.
A couple mitigations techniques:
- Do not train a muscle that feels too fatigued. Most people say "listen to your body". Basically if something feels off, then assume it is. Wait a day and train something else in the meantime. You'll most likely be back to normal the next day.
- Do not train at excessively heavy weight. In RPE scale, stay around a 7 or "three reps in the tank". Don't go above an 8 or "two reps in the tank". Training to technical failure could cause you to slip up and pull a muscle that's overly fatigued.
More longer term kinds of injuries that develop over a long period of time may be tendinitis. Tendinitis can develop from constant repetitive motion while putting far too much stress on the tendon. It can be a sign of bad form. Correcting the error can reduce and eventually eliminate it.
Arthritis seems to be a concern among some people. However, There is scant evidence that weightlifting can cause arthritis later in life. Heavier people tend to get arthritis than lighter people. So being significantly heavier because of bodybuilding could, maybe, theoretically increase chances of arthritis. Though weight training itself is not a direct cause of arthritis. To my knowledge, there is nothing that shows a correlation between arthritis and people who are heavier because they weight train. The benefits of weight lifting far exceed any chance of getting arthritis.
Finally, the absolute most extreme injuries I can think of are rhabdomyolysis and, if you're Louie Simmons, a broken spine. If you're training hard enough to be at risk for these, then you're not worried about injuries. Do not concern yourself with them as they most likely will not happen.
There is a saying in toxicology in that "the dose makes the poison". Most supplements from reputable dealers are safe to take at the doses described on the labels. Taking beyond that, you start getting in to potentially dangerous territory.
Although there have been cases where manufacturers push the boundaries of legality and safety to make a more potent product. Though if the product has been on the market for many years, and isn't banned in multiple countries, then it's probably safe to consume. Whether or not they're effective is for another question.
Long term effects of diet
There is a lot of concern about whether high protein diets are unhealthy, particularly for the kidneys.
People with healthy kidneys do not need to worry about high protein diets. People with kidney disease may have to worry.
Most of the other studies I've seen dealing with high protein diets usually are structured in which one group eats an insanely high amount of protein in their daily diet vs barely eating any at all. The thing is, if you're only eating protein, then you're also not eating a lot of other things that you need to function. Not eating foods with vitamins and minerals and healthy fats for many months or years will of course lead to health complications.
Eat your vegetables. Have some healthy fats. Drink a lot of water. Then you should be good.
As brought up in the comments, there is also mental health aspects related to bodybuilding. People who get really in to bodybuilding are at risk of a few issues that I think are important to be aware of.
People who bodybuild, especially in the days of social media, will compare themselves to other people. This can lead to body dysmorphia in which you believe that you're not nearly as fit as you believe. Some people can believe they're way fatter or skinnier than they really are. Some people believe they're way weaker than they really are. This is hard to combat. Just be aware that the most successful people on social media are typically either on the upper end of the genetic spectrum, on PEDs, or both. They also live lifestyles that let them have the physiques that make them appealing online, which may not be a lifestyle you can emulate.
Body dysmorphia can lead to becoming obsessed with fitness. People will just workout constantly. Spend every minute of free time in the gym. Unfortunately, this obsession may be necessary for those that are trying to compete (because let's face it. Your competition is obsessed). The average recreational person should not have their life ripped up.
This obsession can also lead to eating disorders. This can lead to eating in a very unhealthy way. Anorexia and bulimia are the most commonly known, but there are other types. For example, a lot of people will pick and choose a diet they believe will lead them to their goal, but they don't have the nutritional know-how to eat that diet in a healthy manner. So they will eat that diet in the most extreme way possible which means they're cutting out nutrition from sources that they need to be healthy (see earlier comments about not eating vitamins and minerals). These diets are sometimes also so restrictive that people will reject any kind of social life that may cause them to break it. If your diet starts pushing away your friends and family, you have a problem.
I do not have the training to know how to break away from these traps if someone falls in to one. To help stay out of them, just keep in mind that perfection is not always obtainable. Try to go half-way there, and you'll still be better off than 99% of the population.