not sure if I should ask here or on the judaism one.
I have heard that Muhammad created the prayer services based on the Jewish holiday of yom kippur, and that explains 5 prayers a day and bowing down. Is there evidence to support this/is it right?
The Islamic doctrine is that Allah commanded the Prophet Muhammad ﷺ to observe five daily prayers on the night of Isra and Mi'raj. There are hadith on that in various collections (for example see this one). Next Gabriel came and led the Prophet in prayer at the appointed times (see this hadith)
I am not aware of any tradition that the Prophet observed the Jews on Yom Kippur, there wasn't any prominent Jewish community in Makkah, where the prayers were first instituted.
According to Islam, Allah sent the prayer and it's instructions during Mi'raj. Prophet Muhammad (SAW) did not create the prayer services by himself. There are many similarities between Judaism and Islam, not only regarding the prayer, but the restrictions and rules (The concept of kosher and Halal-Haram etc), which is obviously because both are Abrahimic religions. It does not mean that one copied another, rather it's because the origin is same.