It was reported that the Prophet (pbuh) said: “The image is the head, and if the head is cut off, there is no image.” It was included by Al-Bayhaqi in Al-Sunan Al-Kubra (7/270) and Al-Aqeeli included it in Al-Du’afa’. Al-Albani authenticated this hadith chain, as in “Al-Silsilah Al-Sahihah” (4/554).
If the image or logo on the shirt is an image of a living soul and it lacks facial features and details, it should not be a problem as the forbidden image in our faith is the one that details the face.
As for clear images of living souls on clothing, those types of images should not be worn especially during Salah. Unclear and hidden images, like those on the inside of the collar, don’t take the same ruling and might be worn because the facial features are not shown. If the problem with images becomes so widespread in children’s clothing, and an image appears in a partial, incomplete form, then perhaps it may be forgiven.