Hello,
If your JEE Main photo does not have a plain background, it may get rejected because the NTA guidelines clearly mention that the photograph should have a plain, preferably white background. Even if your face is clearly visible, not following the background rule can create issues during verification.

If the correction window opens, you should upload a new photograph that follows all the required guidelines (plain background, proper lighting, no shadows, recent photo).

If the correction window does not open, then usually NTA still accepts photos if the face is clearly visible and the photo meets most guidelines, but it is always safer to re-upload a correct photo whenever the correction facility becomes available.

In short: wait for the correction window and re-upload a proper photo to avoid problems.
Hope this helps you.