If you're any kind of power user, then yes you should upgrade both as you'll see massive speed increases (see my signature for all that I do with it). However if you're just doing vanilla stuff, it likely won't matter one bit.
Oh it's just the dev build that does that, if you want those messages to go away the easiest method is to download the production build. It's the pixi.min.js file. Then just rename it to pixi.js and overwrite the one in your game's folder with it.
Technically it's also a bit faster as well as it removes all extra spaces and warnings. Though the downside is you will have a hard time messing with the pixi.js file directly if you do that. But aside from that it's probably the better option for 99.9% of users.
Damn. We’ve gotten so close to 0 reports, 0 approvals a few times over the past couple weeks. Does it matter? No. Is it realistic. No? Do I rely on your reports and want everyone to keep posting. Yes. Do I 100% games? …sigh… Yes.
Here's a tutorial I did on how I made my Leonardo A.I.-assisted artworks for my game's recent update.
Disclaimer: This is meant to be a band-aid solution for people like me who aren't good artists or don't have the financial means to hire an amazing artist. If you have the means, please buy commissions and support your fav artists.