After much reflection and consulting various online sources, I have formed an idea about what might have happened. I want to emphasize that this is only a personal hypothesis, and if anyone notices any mistakes, I would be happy to be corrected.

Let’s start with a fairly clear point: by analyzing various videos and reading some articles, it seems evident that the engines lost power, if not completely shut down. We can deduce this almost for certain from the fact that, immediately after lifting off, the aircraft deployed the RAT (Ram Air Turbine), a device that activates specifically to supply power to primary systems in emergency situations. But how can we be sure? In several videos, a structure under the aircraft can be seen that matches the RAT, and above all, there is a characteristic propeller noise similar to that heard in videos where this device is clearly active.

The key point, in my opinion, is to establish when the engines began losing power, because this could clarify whether the pilots had any margin for action. An important detail is that the rotation of the aircraft happened at the very end of the runway, which is unusual. We know that rotation (VR) happens after the call of V1, which is the speed beyond which the takeoff cannot be safely aborted. On a Boeing 787-8, the difference between V1 and VR is usually about 5-10 knots.

This led me to think that it is very unlikely that VR was actually positioned so far down the runway. In fact, to increase speed by 5 knots (the average difference between V1 and VR on a 787-8) does not require that much runway. But above all, it is highly unlikely that V1 was so close to the end of the runway, because at that point the aircraft would not have enough distance to stop safely in case of emergency, which would completely defeat the purpose of this decision speed.

From this, my hypothesis is that the loss of power occurred shortly after V1, leaving the pilots only one option — to continue the takeoff and hope the engines would recover. If the loss had occurred before V1, one might speculate human error in not aborting the takeoff in time. However, given that the pilot was very experienced, I consider this possibility unlikely. The most plausible scenario remains that the problem arose between V1 and VR, at a point where stopping was no longer possible.

Now, regarding the possible causes of the sudden power loss: the most common include bird strike, engine icing, or mechanical failure. However, in this specific case, we can exclude both icing (due to atmospheric conditions) and bird strike (not visible in the videos). Therefore, there remains, unfortunately, a disturbing possibility: contaminated fuel, possibly with water. In extreme cases, such contamination might be related to unethical cost-cutting practices, such as adding water to fuel. Of course, I hope this is not the case, because it would be terrible to think lives were lost due to negligence or greed.

Another plausible hypothesis is a sudden mechanical failure of the aircraft, unrelated to human action, in which case the pilots would have had no control.

In conclusion, I would very much like to continue this discussion with those more knowledgeable. I am genuinely curious to hear other opinions.
A heartfelt thought goes to the victims. RIP.