I left Alberta (Edmonton) in 1996 for much the same reasons. Moved to Toronto to take part in the .com thing. It's an ongoing cycle and seems to get worse on the downside of every bust.
Sometimes I imagine going back, because my elderly parents are there and my brother is there and I still have lots of friends there. But I can't imagine transplanting my children into that province.
I usually think of politics as a country-level issue, so it's hard for me to understand your point - can you elaborate on how does "toxic politics" on a city level look like that would make me not want to live there?
Poor quality of municipal services caused by e.g. waste and corruption; or something entirely different?
You're missing a level with this - the provincial government is the issue. If you're American, think of how Florida has been dealing with COVID or how Texan electricity policies have affected things lately - it's that sort of thing. The provincial government launched us into the #1 COVID spot in Canada (we were competing with some of the worst America states for a while) and they have consistently doubled down on bad bets and bad policies focusing on what used to be rather than accepting the new reality that Alberta needs to start planning for the future.
They likely mean Alberta provincial politics, which are kind of a mess. The current provincial government has done poorly with the COVID situation, and has spent as much effort battling cartoons on Netflix for being too "anti oil & gas" as anything.
Municipal politics aren't toxic in Edmonton and Calgary, they've largely managed to avoid the partisan divide that has poisoned discourse at the provincial level.
Canada is a highly federal country. In some ways even more so than the US. The political situation differs a lot between provinces, and the provincial governments have a lot of power.
And Alberta has essentially been a one party state under conservative rule for the last 50+ years (minus one 4 year term where a nominally left wing party took power by "fluke" because of a feud/split in the conservative vote). Every position of consequence there is connected to the conservative party, which is connected in turn to the oil and gas industry.
Sometimes I imagine going back, because my elderly parents are there and my brother is there and I still have lots of friends there. But I can't imagine transplanting my children into that province.
Like you said, the politics are toxic.