One of my multi-region clients is also affected by Brazil GCP.

And also that effort(multi cloud) >>> effort(multi region)

This isn’t a whole-cloud outage. It’s not even a whole-region outage.

Whole-cloud outages are pretty damn rare. The recent GCP issues are an exception to the general rule.

I’d posit that the complexity of a multi-cloud setup is generally going to reduce your service’s reliability more than relying on a single cloud does.

I've maintained a large multi-cloud architecture in the past. The problem is they really hit you hard on egress costs. Of course the motivation is obvious, they want to keep you locked in to their vendor. I did like that it gave a stronger leverage in contract renewals, but that was about it. The IAC was much more complicated and required more people/areas of knowledge. So it's definitely a tradeoff.

You are correct that it's "better" though if your goal is to have as many 9's of uptime as possible.

Every time pager duty hits, take a shot

I dunno. If just your employers site is down then you'll be expected to fix it, whereas if everyone is down there's less pressure.