OK the new version upgrades to mathjs 15 (from 9) and vendors it in https://observablehq.com/@tomlarkworthy/mathjs
GLPK v5 (up from 4) which actually has its own postMessage handler so that removed a load of bridge code between the LGPL area and ISC area.
The fuzzer tests got moved inside. The webcode footer and old testing framework was removed, in preference for test_ python reflection style (https://observablehq.com/@tomlarkworthy/tests).
@jwoLondon improvements to canonicalization were folded in and attributed Canonicalization with Math.js / Tom Larkworthy | Observable
Happy to hear you found it useful! Its been copied to my website as well now.