Flash player built in?
When Chrome and Firefox started building in flash player, I removed Adobe Flash Player from my PC's and forgot all about this flimsy update prone security hazard.
In the mean time I happily switched to Vivaldi and all was well for a long time until recently when I discoverend that, in order to watch certain media sites (e.g. www.npo.nl), I'd need to install Adobe's Flash Player again. Which I have, reluctantly.
Does Vivaldi have plans to build in a flash player, like Chrome and Firefox do?
No, Vivaldi will not have Flash as builtin.
I f you need Flash Player you must install Flash Player (PPAPI) https://help.vivaldi.com/article/install-flash-player-for-vivaldi/
When Chrome and Firefox started building in flash player
Firefox doesn't have flash built in. It requires you to download and install the NPAPI version from Adobe. Chrome and Vivaldi don't support the NPAPI version anymore, but you can download and install the PPAPI version that they can use. But, Chrome already includes it in its installation where it's basically built in, so you only need to download it for Vivaldi and Opera. Firefox doesn't support the PPAPI yet (and they weren't planning on supporting it at all until recently).