<p>I have a problem in regards to filament jam, however I don't think that my case is any related to the extruder nozzle.
After 30 to 40 minutes printing my filament bends and get stuck on the tube entrance.
To print a nut wheel which comes as a demo file, I had to repeat the operation 4 times, and I had to stop printing when it got stuck, and continue with the printing, which led to a small imperfection.
What's the problem? The filament? The printer? Myself?
I have a Voxelab Aquila (completely new) and the filament u just a generic PLA from Amazon.</p>
<p><a href="https://i.stack.imgur.com/SkWzF.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/SkWzF.jpg" alt="Filament jam" /></a>
<a href="https://i.stack.imgur.com/Hs1qY.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Hs1qY.jpg" alt="Filament jam from another angle" /></a></p>

Something is stopping the filament from going down the tube 30 to 40 min. after you start printing.  You are correct that this doesn't sound like a clogged nozzle.  It could be deformed filament, but the closeness of the timing after the start sounds like heat creep.  Other possibilities are also listed at the linked stackexchange article.
Note: with heat creep the filament will not jam in the tube.  It will jam just above the nozzle on a Bowden tube extruder; thus the filament stops going down the tube.  The tube entrance is probably the largest location the tube can kink, although not very large.
What are ways to avoid heat creep?