Hi there @nachenko
Yep, it's amazing how vocals can push a track forward and give it a completely different feel, nice voice & vocals BTW.
I can also pick up those "glitch-y pops & clicks" in the mix as mentioned by @kuchenchef . It looks like it's coming from the vocals. Did the singer used any auto-tune or voice processing effects while recording ? That could be one reason, another one is if you processed those vocals afterwards. Suggest you play the vocals in isolation, stick a low cut filter on an EQ and monitor with a FTT visualizer such as Voxengo Span, you should be able to pick up those picks. It could come from something else but it sounds like it's happening only when the vocals are playing. So yep, you need to troubleshoot this.
Levels wise, either you crank up your vocals or you reduce the musical parts IMO, vocals are sitting a bit backward at this stage I think.
Arrangement wise, I would rather introduce a big hook ( with synth & guitars ) at 2:50 instead of this quietest part.
For vocals mixing in the context of synth-wave, retro-pop wave, maybe you could get some nice tips from Michael Oakley tutorial ( video 11 ) like the vocal-reverb-reverse trick and in general I found his course very nice to follow and with a great approach to making this genre.
But yes, first thing is to troubleshoot those glitch-y sounds for now, looking forward to hear how this track evolves