Sprinkler leaks broadly speaking look as soggy spots, low tension, or bubbling at heads
https://holdenduog620.theburnward.com/preventative-sprinkler-maintenance-that-saves-water-and-cash
Sprinkler leaks traditionally appear as soggy spots, low strain, or effervescent at heads. Inspect risers, lateral lines, and valves, then fix cracked fittings to restore device overall performance.