Primary and secondary ETV curves (red and blue circles, respectively) formed from the TESS observations with the best-fit photodynamical solution for TIC 351404069 (see Sect. 5). The dynamically forced, rapid apsidal motion of the inner, eccentric EB is clearly visible. (It is important to be aware of the huge amplitude of the ETV.) The horizontally centred black curve represents the pure LTTE contribution. Vertical lines mark the times of the observed outer eclipses (green – the binary occulting the tertiary star and brown – vice versa).