I work for a smaller tech company and we do large scale events periodically with our customers. We do lots of perf testing and ensure our servics can handle these sustained bursts of usage which can reach upto ~500k users concurrent.

Google flagged our main event site as a phishing site during a large event that was lasting multiple weeks. No matter how many load tests you do, always have contingency for Google.

TDLR: Even if you DONT USE GOOGLE as YOUR CLOUD provider, always be aware of its impacts on your customers/busisness!