I am not talking about the legal aspect in this case, I am not a copyright lawyer so I don't know enough to comment on that, I just point out that this is almost certain plagiarism, there is almost zero chance that you paint a picture very similar to an album cover of one of the biggest bands in the history and then even names it almost the same. I mean sure, some people get struck by lightning twice, but what are the odds?

It's not just the theme, they have almost the same name also "Endless Sea" vs "Endless River".

So if someone would paint a tongue and lips logo and call it "Rolling Granite", would you be so naive that you would say the same thing? "Oh, sure they have the same sort of theme, but how can you call this plagiarism?"

It's obvious plagiarism, the original picture was even posted by the artist on this sub.
https://www.reddit.com/r/Art/comments/chjmvj/the_endless_river_pink_floyd_me_digital_2013/