Minecraft players will single-handedly redefine what "strip mine" means in English, and there's nothing we can do about it.

I’ve heard it refer to the practice of mining every block in a large area, as opposed to digging long tunnels and mining any veins those tunnels run into.

I’m not sure if that’s the definition OP is talking about because it isn’t entirely unrelated to what “strip mine” means IRL.

Dig down to a desirable depth, then start mining in a straight line until a desirable distance, then go back to the main mineshaft where you start, then move 3 blocks away and start digging in a straight line in parallel to the last mining shaft. Your mine will looks like | | | | | | after a while.

It will cover large area right under your base. Not sure if there's a new meta right now but this is what i learned and do a decade ago, and will still be doing if i start the game now. The term is defined by millennial.

Though the IRL strip mining is occured on the surface, Minecraft's strip mining can be of any depth.

Mining in a straight line (a "strip" as in a strip of paper) instead of "stripping the land" kind of strip.