For the purposes of F95 they deem it completed, with the game also moving out of early access to official release signifies a full release as well, and mostly in the AVN world, v1.0 signifies completed.
Example comes to mind about completed would be Fetish Locator, it's been completed for a year now, main story done and everything, but it's had 10 updates or so adding endings and still has one more ending coming. People say the same thing about the completed tag, but usually if the main story is done, they will usually tag it complete.