The next person you see in the squat cage with 20 kg on the bar and a big belt, maybe you can make a comment after reading these few lines... The squat will often only be a quarter of a squat... It's a bit like a child who wants to dress up as a little soldier, he buys the uniform and pretends to shoot.
Wearing a belt without needing it is a little bit the same thing.
We cannot say that the belt is useless since the greatest athletes in weightlifting and powerlifting use it. But apparently, only when they get heavy.
Indeed, a belt will put pressure on the abdomen, in the same way as a good abdominal muscles would. When you perform a movement such as squat, especially if you lift heavy, the abs will work hard: they will solidarize the spine, pelvis and trunk. The slightest parasitic movement or imperfect execution can have disastrous consequences on the integrity of the spine. It is therefore normal for the athlete to use a belt to help his abdominal strap to contain the pressure that will keep the entire area stationary.
What about the one who squats halfway and doesn't take heavy loads? First of all, he will prevent his abdominals from doing their job and thus from strengthening themselves. Helping abs that don't need it will weaken them. So using a belt under these conditions seems like a really bad idea. However, as you get closer to your maximum performance, it would be normal to protect your back. At this point, the belt is fully functional again.
Be careful not to rest on your belt to protect your back either! The belt does not protect your back! The abs will always do it, but the belt will simply help them.
For people who already have back problems or are injured but still want to try movements such as squat, it seems appropriate to prevent some additional injuries with the belt.
Be careful to also remove your belt between each set and not keep it for the entire session, as again, your abs may still get used to it and relax more than expected. Try to keep them in good working order, work them regularly. If you have lumbar problems, you will need to be even more careful and not neglect them. If you experience pain during your training, change your exercises! Adapt your exercises to your particular case, but in any case you can find an exercise that will strengthen your abdominal muscles and reduce your back pain.
In conclusion, don't use your belt to show off at the gym and show that you are a real training kingpin! It can be used to take on more weight and hold your abdominal strap in place, but it must be made of hard material. Elastic belts are to be avoided because when they fail, they will cause even more damage.
Choose a good old-fashioned leather belt as QNT do, for example, or at least in more modern hard materials. But you should abstain if you don't want to take a lot.