Came across this issue updating my system. Portage pulled in installed/existing chromium as a 'rR' rebuild due to dependencies scheduled for update - harfbuzz being one of them. The rebuild of chromium fails the compile stage.
Now the installed version no longer works AND I cannot run `emerge --depclean` as it will fail with:

Calculating dependencies... done!
 * Dependencies could not be completely resolved due to
 * the following required packages not being installed:
 * 
 *   >=media-libs/harfbuzz-2.4.0:0/0.9.18=[icu(-)] pulled in by:
 *     www-client/chromium-91.0.4472.106
...

I'm guessing the update of harfbuzz from 2.4.0 to 7.1.0 may have broken chomium-91.

Chomium-91 is pretty out of date. Maybe a binary version would be better for Funtoo?