Just an FYI to anyone who wants to downgrade back to 64.x (and not to buster's 62.x) you can still grab the deb files from: http://snapshot.debian.org/package/chromium-browser/64.0.3282.119-2/ (64.0.3282.119-2+b2 specifically)
Make sure to install chromium-common as well. You will get a profile downgrade compliant but it hasn't caused me any actual issues.
