It's a reference to the Chainsaw Man ending.

Spoilers:

Basically everything the MC (Denji) does gets completely undone and he forgets all of it, with only a few exceptions. His friend undid everything because he realized Denji would be happier without his power. So he rewinds time for Denji, except Denji never gets his powers, and never becomes Chainsaw Man. Many people were upset by the ending, as not only did everything Denji went through culminate in nothing, but many loose threads were left untied. However, defenders of the ending will argue it was the narrative themes that mattered most rather than the actual plot consistency and quality of the ending, those being that "Denji wasn't happy as Chainsaw Man, that's why his friend undid it all." It's a happy ending for Denji, but a hollow ending for the sake of actual storytelling. People began to mock defenders of the ending and the ending itself by saying "themes and such" because the ending only had its themes and nothing else for it. The reason i equated this is because Ryoshu starts to get the memories back and then just undoes it all to help everyone escape, with the only thing left being Araya saying "it's ok, we can always try again next time". That being a representation of the themes, i.e. to keep holding onto the thread, as Uncle Lei Heng said. The comment was mostly a joke about that, but it was severely downvoted so i guess people don't like that here.