Anytime an artist decides to hop off of Instagram or social media as a whole, it can be indicative of a few things. Some may take it as an artist readying a new album while others hop off in order to avoid social media hysterics, especially when controversy strikes. It's unclear what Trey Songz motive might be but the singer has officially hopped off Instagram. As pointed out by TheShadeRoom, his Instagram has no posts and says "User not found."
Again, there isn't any concrete evidence or word of why the singer decided to call it quits on the 'Gram. It's unclear if this is temporary or not but it should be noted that he also hasn't been active on Twitter since late 2019, although his page is still up. It has been nearly three years since the release of his last studio album, Tremaine The Album. He did, however, drop two mixtapes in 2018, 11 and 28. For all we know, he could very well be readying his eighth studio album.
His absence from social media might also have to do with a recent lawsuit he was hit with. Trey Songz was sued for $10M by a woman who accused him of sexually assaulting her at a nightclub on New Year's Day 2018. It's unclear if this actually plays a role in deactivating IG but it does add to the other allegations against him by other women.