The advice they give is misguided. Many major software vendors were either not vulnerable, or have since released security patches, or provided workarounds so that their users are not affected.
As for FlowCrypt, we released a software update within six hours of the announcement.
Chrome and Firefox extensions update automatically. You can double check you are on version 5.4.8 or higher in FlowCrypt Settings. If you use our Android app, check for updates in the Google Play Store.
We will follow up in coming days with a more in-depth technical review.