The shared chunk that stopped merging
A newer bundler quietly stopped honouring the option that merged the shared layout into one chunk, until the same grouping was rewritten in the form the bundler now reads.
An earlier post described merging the shared layout into one stylesheet and one chunk, which cut render-blocking requests on mobile. A newer version of the bundler stopped honouring the option that did that. The build said so in one line, and the shared chunk was no longer produced, so the layout’s stylesheet and script loaded as separate render-blocking requests again:
WARN manualChunks option is ignoredThe bundler’s newer grouping mechanism replaced the old option. The fix expresses the same module match as a grouping that keeps the small shared group rather than dropping it. The regular expressions that select the modules did not change, and the route that loads the duel stays outside the merge.
The warning reproduced on the branch before the fix and was gone after it. With the fix, the shared chunk appeared in the build manifest with its stylesheet, and four entries in the route map referenced it.