In case you don't feel like untangle the
#CrowdStrike post-mortem, this is the gist of it:
"Based on the testing performed before the initial deployment of the Template Type (on March 05, 2024), trust in the checks performed in the Content Validator, and previous successful IPC Template Instance deployments, these instances were deployed into production."
In other words they simply didn't do e2e tests on the problematic update data that triggered the bug in their parser, because prev updates worked fine.
We still don't know how the malformed Template Instances were produced.