Is Sujood As-Sahw (prostration of forgetfulness) obligatory if one stood up for the fourth Rak'ah, then sat down for the first Tashahhud briefly by mistake, without an additional transitioning Takbir?

If a worshipper stands up without saying the Takbir, their prayer is valid. However, they must perform the prostration of forgetfulness (Sujud Al-Sahw) if they inadvertently add an extra standing, sitting, bowing, or prostration to their prayer, even if it is only for the duration of a brief sitting (Jalsat Al-Istiraha).