Here's the original announcement from 2017. It links to all of the corresponding announcements from the major browsers, which were released in tandem, and detail the individual timelines and roadmaps for removing browser plug-in support in each browser:
https://theblog.adobe.com/adobe-flash-update/
This was covered widely in the tech press at the time, and most of the browsers have included in-product messaging and regular updates on progress towards sunsetting Flash along the way. Five of the first ten Google results for "Flash Player" discuss the impending Flash EOL.
It's been an interesting and exhausting three years on many fronts, and in the context of global events, it seems reasonable that it might not have made your radar. That said, for the industry professionals responsible for managing and planning for their IT resources and services, this change has been well communicated.
As a consumer, there's really nothing you can do here. It's up to content and service providers to migrate, and they've had generous advance notice. The best thing you can do here is to complain to your tax authority, and point them to the notice above, and maybe our enterprise EOL faq. They have less than a month left to avoid a major headache.
https://www.adobe.com/products/flashplayer/enterprise-end-of-life.html