A protective cap
As scientists in the control center eagerly awaited color images from Venus, sad news was announced, "There is a strong signal, but no modulation." All of the protective caps had failed to come off. After the problems on Venera-9 and 10, the caps had been redesigned, but now the results were even worse. An intensive study later determined that a seal had formed, preventing atmospheric pressure from properly equalizing. Thus, many tons of pressure held the caps down and prevented pyrotechnic charges from ejecting them.
There are many sources in Russian, for example:
Automatic interplanetary stations "Venera-13" and "Venera-14". http://galspace.spb.ru/index500.html
«Венера-13» передала как чернобелые, так и первые цветные панорамные изображения с поверхности Венеры. На них было хорошо видно кольцо в основании посадочного аппарата с «короной» из треугольных профилей, предназначенное для аэродинамической стабилизации посадочного аппарата во время спуска, отброшенные крышки камер, цветные тестовые полоски, развернутый пенетрометр ПрОП-В и выпускной клапан аэрозольного рентгеновского флуоресцентного спектрометра на посадочном кольце в непосредственной близости слева от пенетрометра."
Venus-13 transmitted both black-and-white and the first color panoramic images from the surface of Venus. They could clearly see the ring at the base of the landing apparatus with a “crown” of triangular profiles, intended for aerodynamic stabilization of the landing apparatus during descent, discarded camera covers, colored test strips, a deployed PrOP-V penetrometer and an exhaust valve of the aerosol X-ray fluorescence spectrometer on the landing ring in the immediate vicinity to the left of the penetrometer. "
P.S. As a witness to the events at the Center for Long-Range Space Communication personally told me, for the first time no one understood what kind of object it was in the panorama. The object was clearly of artificial origin. The panorama was printed in real time in the hall where there were journalists and television men. The printer suddenly stopped. Journalists were asked to leave. Only after consultation with the developers of the lander, these photos were published a few days later.