I'm not using Reddit in any capacity since they have started giving their content for LLM training, so I can't help you with that, but looking at 4-5 third party applications right now, they all have a left arrow at top left to go back.

They all are very different applications and have very different designs, yet the arrow is there.

To be honest, I baffled at your question for a second or so, because I never thought about that, yet the method is so universal that I was not thinking about it at all.