could be a rendering bug, but the infinite climb doesn't show ANY clue outside the right wall.
and there is no discernible pattern for trial and error.
Hey! Sorry to hear that there is an issue with the riddle on your playthrough :( I'd really like to know what could've caused this. Could you send me a screenshot of the wall outside the cave where the solution should be? Ideally with some information about your system / browser you played the game with. Just to avoid any misunderstandings, you can check the playthrough of Grimbag (15:28) how the hint should look like. He posted his let's play in this comment section.