Security vulnerabilities due to resource reuse (subdomain takeover is just one example of this) are rampant and readily exploitable for tons of major companies, especially as cloud providers and SaaS often overlook these as being client responsibilities.
Shameless plug, I’ve worked on identifying/characterizing these issues on cloud providers: https://arxiv.org/pdf/2204.05122.pdf
It’s only a matter of time before adversaries become more sophisticated at identifying and exploiting these in bulk.