Why does my procrastination get even worse before exams/deadlines?

It can for me too. I've always thought that it is probably linked to anxiety. I know that for me, procrastination is often a way to cope with the anxiety that comes along with whatever I'm trying to do. So say I have a big deadline coming up, that makes me anxious. Because it makes me anxious, working on it, even though it would actually bring me closer to meeting the deadline, brings up that anxiety, and so I avoid it altogether. As the deadline gets closer, not only does my anxiety build just because I'm nearing the time that I'm anxious about, but it builds because I've been procrastinating and am realizing more and more that I've made my life harder by procrastinating already. Would the logical choice be to stop procrastinating? Maybe. But that comes with lots of anxiety. So if I'm needing to avoid that, even more so, as the deadline approaches, I'm going to have trouble getting anything done because my need to avoid the anxiety is greater than my need to walk through the anxiety if that makes sense.

There are many reasons your procrastination may get worse as deadlines approach. The reason I'll discuss is self-sabotage. As a way to prevent yourself from feeling that you're not smart enough, you essentially handicap yourself so that if you do poorly on an exam or assignment you have an excuse for your performance. Instead of a poor grade reflecting that you weren't able to understand the content or complete an assignment well enough, the poor grade reflects that you simply didn't study hard enough. It's easier to accept that we failed because we didn't try hard enough than it is to accept that we failed after giving our all.

I believe it's due to amount of pressure and the thinking that "I might/will fail" that usually comes as characteristic of depression.

The stress of exams/deadlines tend to be a trigger for my anxiety. Procrastination sometimes saves me from that anxiety, but I have to deal with a much higher level of anxiety when I have to rush to meet the deadline. Breaking the task up into small, manageable pieces makes it feel less overwhelming and makes me feel like I've accomplished something, which helps build momentum!

maybe because you are worried of ruining everything, so by procrastination you feel better and more calm now that you don't have to face your tasks. It happens to me a lot, when I am scared about an upcoming exam or assignment, I keep on procrastinating it out of fear until I cant procrastinate anymore

Having experienced this tendency as a student myself, I believe it may have to do with your level of anxiety and pressure you feel in anticipation of doing an exam or reaching a deadline. Indeed, such events are often rather stressful for students, whether it be due to fears of not being able to complete the task or not being able to meet certain expectations, so perhaps this may be the case for you too. This can apply to workplace contexts as well, where employees often have to meet strict deadlines. It is common for one to resort to procrastination as a way of coping with anxiety, as such feelings tend to be paralyzing. Procrastinating can then be seen as a form of distraction; after all, it is easier on the mind in the short term to focus on things that provide more positive emotions than to deal with stressful situations, which provide more negative emotions. Unfortunately, the relief is only temporary and in the long run you will have to go through the exam or deadline. The important thing is to identify and understand your feelings to better deal with them so your mind doesn't feel the need to rely on procrastination as much.

As exams and deadlines approach, the pressure to succeed goes up. Sometimes it is easier to to ignore that pressure by procrastinating.

Procrastination can get worse before exams/deadlines because we can see these moments looming before us and we are trying desperately to avoid them because they are either boring, uncomfortable or stressful to deal with. Putting the work we have to do out of our minds with procrastination can provide temporary relief, like a band-aid on a wound.

Different people handle deadlines (and procrastination) differently. For some, getting closer to a due date results in a "fight" reaction, a drive to work harder and get it done. For others a "fear" reaction or giving into the assumption they wont make it anyway. Its important to not let fears and doubts rule your behaviour. From your question I would say you have already recognised the problem. The next step is to address it. Fight past your fears and doubts, focus on the task at hand. Break it down into smaller more manageable tasks and take them on one at a time.

This may occur because the work load may be great and seem increasingly difficult so the first thought that comes to mind is maybe later and this may be very hard to come out of it helps to dedecate time to this tasks and create a suitable environment for this task