New players get lost there often because they don't have HM05 - Flash yet, this happened to my friend as well. (i had flash already and was able to find him)
This problem makes the very-early game experience bad because they got lost in a maze while seeing close to nothing.
New players might forget to talk to Jerry and recieve the free escape rope

My suggestion is make the Team Rocket grunt at that stole Jerry's pidgey block players from going deeper inside the maze and once beaten make him stay there until the player has obtained HM05 - Flash

Thank you for your time

Tbh, idk if it should be blocked, but I can 100% assure there should be a big warning for newbies that get confused and think that's the way to go to Pewter City. I see newbies just quitting because they get lost there and can't get out lol. I have no idea how to fix the issue, as the Dragon Rage TM and the Abandoned Pokemon can help a lot for the first badge.

I agree it might need changes.

yea don't add an NPC infront of it, maybe like a signpost beside it, but doesn't the miner NPC that's beside it already say that it's dark in there and to not go in?
Early on the loot in the maze is very useful, dragon rage is there which can easily beat the first gym, and the second, and then there's also a free pokemon in there that can be very useful depending on your starter

Yeah, IMO there should be a warning saying it's not the way to go to Pewter City.