>If a brand of CGMs have an issue that sometimes causes false low readings

Not sometimes. "Over an extended period".

"Abbott Diabetes Care stated that certain FreeStyle Libre 3 and FreeStyle Libre 3 Plus sensors provide incorrect low glucose readings. If undetected, incorrect low glucose readings over an extended period may lead to wrong treatment decisions for people living with diabetes, such as excessive carbohydrate intake or skipping or delaying insulin doses."

Months of high blood glucose level can worsen patient's condition or if high enough even put them into hyperglycemic coma in weeks(?).

[0] https://www.fda.gov/medical-devices/medical-device-recalls-a...

While true, you would have to ignore all other indicators for quite an extensive period of time. Like excessive urination and hypersensitivity being obvious ones. Not impossible but I have the strong sense there is more to this story than reported in the FDA disclosure.