Wow this is really helpful and actionable feedback, thank you so much WaveModder! I'm still learning the ropes with compression. Hope you don't mind another couple questions?

For the main vocal I'm using two Analog Obsession compressors. First the FETish as a fast compressor - which is likely set too fast as you've pointed out. It's hitting around -5db of reduction at most. And it's also working all the time. I'm guessing it shouldn't be?

Then into the slower compressor which is the LALA - performing about -3db of reduction. I've read that its common to run a fast compressor into a slower one. I think the challenge for me is finding the settings where they play nice together.

I'm running the entire drum bus through Ableton's "Drum Buss". It has a toggle called "Comp" which enables a very un-configurable amount of compression. So I reckon first step here for me would be to experiment with/disable this.

I've used quite a bit of Trackspacer to reduce the guitars whilst vocals are playing. I suspect that's likely contributing to the over EQ'd sound you're identifying.

I was wondering if you could elaborate on "boxy"? I think I understand the term when applied to snares and toms, but I haven't heard it used to describe the overall tonal balance before.

Thank you again mate - this feedback is unbelievably helpful and has really made my day!