Non-rebreather taper to room air

[IndependentMN]

I work in a home care setting and one of my patients uses a non-rebreather mask with the side port tabs removed. Protocol states to start flow rate at 8LPM and once 90% reached start to taper to room air by 1L per 10 minutes. Is this safe? And if not can you help me understand.

I'm aware the side ports were removed so that the bag will be less likely to deflate on lower flow rates but we had a situation where an aid tapered the patient to 1L on the non-rebreather and she was satting at 100% but was cyanotic (blue nails and lips) and I feel its due to improper use of the non-rebreather/taper.

Thanks in advance