Using Good Rx + Pdp or MAPD

For the Medicare Part D or MAPD insured, are any downsides to using Goodrx
coupons ? My selling is in the Carolinas and am just hearing people using this with good cost savings.

Understand for Donut hole calculations, using Goodrx does not include "retail cost" numbers to Medicare rx annual calculations. True?

Anything else we shd know about them ?

Thanks in advance.;)

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