...an Invisible entrance opens to an extradimensional space that lasts until the spell ends.
After thinking about it for a while, I started to wonder if I was wrong. This sentence can be taken two ways - either the entrance lasts until the spell ends, or the extradimensional space lasts until the spell ends.
Anything inside the extradimensional space drops out when the spell ends
implies that the space ceases to exist when the spell ends. But this is different from similar destruction of bigger-on-the-inside spaces, such as the Bag of Holding:
If the bag is overloaded, pierced, or torn, it ruptures and is destroyed, and its contents are scattered in the Astral Plane.
But another spell, Mordenkainen's Magnificent Mansion functions incredibly similarly to Rope Trick, where anything left inside will be ejected when the spell ends... This may be a difference between spells and magical items that do similar things. So this question could easily apply to MMM too.
I do not believe that the answer to this question doesn't matter. For example, Thomas Markov's question could get a clearer answer with the answer to this question. For example, a creature within the space gets banished, and the spell ends before the creature comes back. If the space still exists, it could be that the creature ends up back in the space without getting ejected, since that only happens at the time of spell-end, effectively trapping the creature. On the other hand, if the space does not exist any longer, who knows what would happen? (Hence the question by Thomas Markov). And, if these kind of spaces apply to magical items as well, it is very related to the question I referenced above, as well as this one linked by Someone_Evil.
Taking the English meaning, if I say "A hole is cut in a wall 2 feet wide", the subject of the sentence is the hole. It's not the wall that's 2 feet wide, it's the hole. Similarly, it can be read that the entrance is the subject of the sentence, which is the thing that lasts until the spell ends. But, it could also easily be said that the only reason the entrance exists is because the space was created...
So... Does the space get created and cease to exist when the spell ends, or is it the entrance?