Weekly water changes can advance Cyano /Dino if we strip the environment of nitrate and phosphate.
You post levels R good, your good, my good, their good, all may be vastly different.
What are those levels now?
What do they do week over week.
Cyano loves unstable chemistry.
It’s like adding bacteria in a bottle, and that may fuel Cyano to some degree.
Get a read on all parameters and their daily/weekly flux will help to narrow the “what” might be outta wack in chemistry.
Once you correct the cause, you can chemi-clean what’s left…. Gone in 48hours.