> because I didn't get my way

if you cannot come with compromise, and if it's only about some code/architecture/software, let it go (and fail or whatever), esp. if you have not invested man-years actually building it yet. If you go ahead and invest yourself, even if it works, it might still be shot down for political reasons - and you'll feel much worse. Event sourcing - and bitemporal stuff - is not a simple thing - and might be completely misunderstood. Correctness it brings does not pay checks - unless required at the root and/or accepted at whole-human-chain. Been there.

> I feel like taking up that offer..

if it's under different boss - yes. The grass might be greener there, try it out. Otherwise.. working against oneself's beliefs/ways is recipe for bad burnout. Been there too..

> Last year, some heads-of-engineering have been happy with my work and told me they want me leading my own team. I feel like taking up that offer, but it will look like I'm just being a spoilt sport because I didn't get my way, and really I don't even know if I can argue against that.

Take up the offer. You either step up into these roles and lead or you end up being led by someone else.

It seems like this company is on its way to a toxic workplace. And you are just an employee, not a co-owner. You even mentioned earlier in another submission that you would like to start own business. Focus on that! Look for a new job in the meantime if you need it.