It is true though that GCP sometimes sunsets specific product functionality, requiring changes on the customers' part. Some of these are unavoidable (eg committing to apply security patches to Python 2.7 given that the rest of the world is mostly not upstreaming these patches anymore), but not all of them.
I would certainly use Cloud Spanner externally now that I've left the company, and IMO spanner has such a compelling featureset that it's a strong reason to use GCP for greenfield development. The problem though is that it's only available on GCP, and could become expensive at large scale.
My newer employer is AWS. Their offerings are a lot more stable and support is helpful.
If you want to build a serious business I would avoid GCP. Google doesn’t really give a shit at winning Cloud. Ads is their core business.
I have definitely enjoyed using AWS support. But I've also encountered some broken/janky functionality (eg using custom domain + api gateway + websockets + Lambda for the apparently niche-task of having a real website use the Lambda-websockets integration) on AWS that I don't think would have made it to production at Google. I also really dislike how they handle project-level logging compared to how it's done on GCP.
Ultimately I do think some GCP products like Bigquery, Cloud Run (I'm biased here), and Spanner as well as general DevEx/reliability factors are compelling enough for GCP to be worth serious consideration, even if AWS offers better support.
A good example is probably IoT. I've heard first hand anecdotes of very difficult migrations off this service.
I was also an old app engine user, but bailed ages ago (original app engine).
Not that it’s any solace to those affected.