I have pulseway 9.9 running on 100+ solar-powered Raspberry Pi B+ (Raspbian Buster). They have been running smoothly for over a year, however within the last month on approx. 30 of them, CPU utilisation has increased from 5%-10% to 95%-100%. Stopping pulseway stops the issue and starting again resumes it.
How to go about diagnosing problem?