Hi @notsolowki,
Welcome to forum!!! Plotly follows the d3.js rules for tickformatting. if you are printing
help(go.layout.YAxis.tickformat) you’ll find a link to d3.js
https://github.com/d3/d3-3.x-api-reference/blob/master/Formatting.md#d3_format, where it is explained how '%' works:
percentage ("%") - like fixed, but multiply by 100 and suffix with "%".
Hence to get displayed the right information in the trace definition where you pass the y-values to be displayed as percentage just divide those values by 100.
If you read the log file as a pandas data frame, then define
y = df['percent'].values/100