Yesterday, while updating dependencies on some of my addons, a dialogue box popped up with the flash player logo claiming that my flash player was out of date. Like an idiot I clicked okay and it began to download a plethora of apps to my win10 pc, that I can only think were some type of malware. Luckily my protection anti-virus etc. stopped it from changing anything and I was eventually able to root all the little bugs out (I hope) before they were able to do anything more devastating than just annoy the heck outa me, but I wanted to sound an alarm just in case (I used to have a student named Justin Case, true story) it was something lurking on this site and not something from the seedy underbelly of the web that circumvented my firewall.
Lua AddOns themselves can't really contain virus's, it's just text and maybe some graphics. I would say it's more likely a bad ad triggered the message. We will certainly audit our ads we even subscribe to a service that is supposed to scan for bad ads they try and sneak in. If you had any other websites open in your browser with ads at the time it could have come from there too.
Flash Player has long been replaced with HTML5 which doesn't require external software. Unless you have some very specific website that still requires it, you really do not need it.
Adobe has also announced that support for it will be discontinued with the end of 2020. You may as well just uninstall it now.