pfr What did you do here?
I don't think firefox
will be the only package that is broken. If/when updating textproc/icu
across major versions, you need to rebuild every singel package that has any, direct or, indirect dependency on it.
If you are using precompiled binaries, chances are the build took place in between the icu
update and the required REVBUMP of all dependencies.
In which case, you need to wait for the next bulk-build in order to get this sorted out.