Mesobotox procedure on cheeks for open pores - but my cheeks completely got flat - How long would it take to recover?

Thankyou for your query. Most effects of botulinum toxin are gone in about five months, some sooner. Please discuss your concerns with your physician who can examine you and also discuss their experience with “mesobotox”. All the best!

It sounds like the mesobotox may have affected the muscles responsible for smiling and cheek volume. With 20 units per cheek, it's a fairly high dose, and effects like flat cheeks or smile changes can happen if it spreads too deep.
The good news: Botox effects usually wear off in 3–6 months, and since it’s already been around 10 months, situation would have been normal now.
Light facial massage or muscle stimulation may help in such cases, but mainly it just needs time. If you’d like, we can guide you through recovery and plan safer dosing next time.

This simply means a wrong technique of delivery was utilized for mesobotox delivery. The depth of mesotherapy is very superficial hardly just a few millimeters and should not have been deep enough to reach the facial muscles such as rizorius (reason why smile is affected) or masseter (reason why your face has slimmed down). Sadly there is no reversal and might take 1.5-2 months+ for wearing off.

I'm sorry to hear of the results from your Botox treatment. These effects are temporary. Botox wears off gradually, typically over three to four months for many patients.