Something weird just happened, I entered the nether to find some ghast tears, and when I came back, the trident was in my inventory. I can guarantee you that the trident was not in my inventory, at least before I entered the nether. Anyway, thank you for your help and time!!
I was there waiting for 10 seconds, as you can see in the picture, the shore isn't that far away. And yes, I tried both, I checked all my inventory slots and I closed the world and I opened it again.
Justerfrog, tridents do not slow down in water. But well, now it is resolved. 🙂