This sure seems on the up-and-up . . . Medicare advantage

Addressed to my spouse with T2 diabetes - private insurance brokers were apparently given access to her health information to market to her (Note the title, specific to the disease she has)
No readable express clue on either side of the post card that it is an advertisement for Medicare Advantage.
If you know how Medicare Advantage works, the reference to extra funds added to your social security does at least give you a hint
The only express disclosure that this is related to Medicare Advantage is in the teeny teeny teeny tiny print at the bottom, which virtually no one old enough to receive Medicare can read. (It took me 3.0 readers and a strong light.)
We do not offer every plan available in your area. We represent MA organizations which offer multiple products in your area. Please contact Medicare.gov or 1-800Medicare or your local State Health Insurance Program to get information on all of your options. Availability of benefits and plans vary by carrier and location. You will be directed to a licensed insurance broker to complete your review.
And the postcard still doesn't tell you who the entity is that has your private health care information, which it is using to market to you.
Time to dump Part C or, at a minimum, subject it to regulations which restrict access to private health information and which require it to act like a reputable business.