The ex-child star posted a new video on social media this week -- this after the explosive doc about Nickelodeon aired -- and JP doesn't seem willing to address the elephant in the room ... 'cause he's just doing silly TikToks without talking about what's on everyone's mind.

The clip features Josh lip-syncing to some goofy audio ... relatively meaningless considering his one-time peers are speaking out, and people are pissed that he's choosing to ignore it.

Check out his comment section in this post -- as well as other recent TikToks of his -- and you'll see exactly what we mean ... hundreds of people are slamming him for remaining silent on the doc and acting like nothing's going on, calling on him to say something.

One person wrote, "your silence is LOUD brother" ... and another added, "*sigh* Josh you disappointed us" ... and yet another digitally shouted, "JUSTICE FOR DRAKEEEE."

Like we said, Josh hasn't uttered one word about the documentary or Drake -- but considering their recently rocky past, including a very clear falling out, perhaps it's not surprising that Josh isn't running to support his old costar during this difficult time.

If you're unfamiliar, Drake and Josh have NOT been close at all of late -- and their apparent feud bubbled up when Josh get married several years ago ... a wedding to which Drake wasn't invited, and which he was very upset about at the time, making gripes quite publicly.

There was a lot of back and forth over this, and in the end -- Josh made clear that him and Drake simply hadn't stayed in touch after their show ... in other words, they're not friends.

They had a sweet reunion at the 2017 VMAs -- but even after that, there seemed to be bad blood ... so on its face, it's somewhat understandable that Josh is looking the other way.

Still, many feel like he should talk about this regardless -- because the issues being spotlighted on 'Quiet on Set' are obviously bigger than any petty beef they might have.