Hover_data of Date type values are displaying in strange behavior

Hi guys, i need your help! I am trying to understand and customize hover_data option of my plotly timeline chart
Here is what i get with default hover_data values:

fig = px.timeline(df2, x_start='Start', x_end='Finish', y="Планета", color='Тип', 
                              #'Start': '|%d',

Both dates are ‘pandas._libs.tslibs.timestamps.Timestamp’ class but they look different for some reason. But the fun part starts when i try to work with them using info from this article https://plotly.com/python/hover-text-and-formatting/

As you can see it doesnt find any signs of Date there (i suppose thats what NaN stands for)

Please can somebody help me understand why Dates look different on the first screen. And maybe somebody have working example of timeline with custom hover_data?
Thank you

Any clues?
Maybe some of you have project with custom Date hover_data values?
Or have any ideas what format of Date values will work?

Still trying to figure it out…
Still no success…