I've heard speculation that the episodes aren't being aired in the intended order, and that Devil's Chord was brought forward and added as a second episode to coincide with Eurovision.
There's definitely something that feels a bit disjointed about this season, and I'm still not sure why they seem determined to shoehorn Ncuti singing into every single episode (at the start of Boom I joked to my SO that if they manage to fit in a song into this one while he's stuck on a landmine I'd be very surprised, and they actually did) but also it's RDT, so having a season be completely bug shit bonkers and then tying it all up together at the end in a clever way would be pretty on brand.
I'm just gonna trust that he knows where he's going with all this lol.