Default Renko brick sizes are calculated using an automated algorithm, such as Average True Range (ATR), that processes recent price history.
Because desktop browsers load a deeper historical data buffer than mobile apps to optimise mobile data usage and performance, the algorithm calculates volatility over different amounts of data on each device. This results in slightly different default brick sizes.
To make the chart identical across both platforms, change the Renko brick size setting from Auto to a fixed, manually entered value.