Large bundle size

Hi, I followed webpack.release.config.js and compression-webpack-plugin for Brotli compress

I got a biggest chunk (majorly Viewer) for 2.82 MB, (for Brotli 539KB, and for gzip 715KB), such as following figure

The reproducible repo is https://github.com/cywhale/preact_cesium

My webpack config is in https://github.com/cywhale/preact_cesium/blob/main/config/preact.config.js

Is there any chance we can further reduce this main chunk size, or any other tips to split it to sub chunks, or just skip some unused modules that concatenated in cesium Viewer?
Thanks.