For MySQL RDS, performance insights aren't available on the small and micro instance sizes. There are also engine requirements. Found here: https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_PerfInsights.Overview.Engines.html
"8.0.17 and higher 8.0 versions, version 5.7.22 and higher 5.7 versions, and version 5.6.41 and higher 5.6 versions.
Not supported on the following DB instance classes: db.t2.micro, db.t2.small, db.t3.micro, and db.t3.small."
Enable performance insights for t2.mediumasked 4 years ago
Performance Insights disappeared after upgrading to MySQL 8asked 4 years ago
Query Plans in Performance Insightsasked 2 years ago
Performance Insights Counter Metrics and Database Load graphs not visible.Accepted Answerasked 3 years ago
Can not turn off Performance InsightsAccepted Answerasked 5 months ago
Performance Insights and MySQL 5.7.22Accepted Answerasked 3 years ago
Error when modifying db.m5.xlarge RDS MySQL for Performance Insightsasked 3 years ago
Does enabling performance insights for mysql rds require restart?Accepted Answerasked a month ago
Feature request: show full MySQL statements in Performance Insightsasked a month ago
Performance Insights option missingAccepted Answerasked a year ago