I don't think AWS says so explicitly, but it's commonly known that T2/T3/T4 use live migration to balance workloads across hosts. This is necessary when oversubscribing hardware (which is the explicit purpose of these families) to avoid hot spots. This may be the "runtime interruption behavior" that the author sees. Use an instance family with dedicated CPU capacity if this matters to you. With T2/T3/T4 you are explicitly asking for variable performance to save money.
For sure — the interesting part to me isn’t that burstable infra varies. It’s that the variance barely showed up in the normal benchmark layer at all while the sustained workload behavior started separating underneath.
Testing for diff scenarios and building a dataset to show perf deeply and broadly to help with decision-making. Trying to dial in the true bang/buck.
No kidding; t3 instances definitionally have variable performance.