What is the best option to restore my lower face after Masseter Botox caused sagging? (photo)

you have early sagging I dont think this Is just fromthe botox I would suggest an internal evaluation like hormonal workup (see link to our physician who does this from a far) but you will need an early face/neck lift if you do not want that agressive treamtent then threads, morpheus, fillers, and/or facetite or accutite can help. do not do botox again.
With significant neck sagging you would need a neck/face lift with muscle tightening (platysmaplasty). at the same time lasers (fraxel,  co2 or erbium( or microneedling RF (fractora, intensif) can be . performed to improve the crepe skin or wrinkles.  You need a formal consultation, as the neck can be treated with a combination approach:
1. micro needling and lasers for texture
2. botox, disport or xeomin to help platysmal bands
3. intensif or fractora RF microneedling for crepe skin and lifting
4. fillers like belotero, restylane silk, juvederm volbella to improve lines and folds
5. neck/face lifting if sagging is prominent or early starting +/- platysmaplasty (muscle tightening)
6. J plasma/Renuvion, thermiRF, inmode facetite for internal tightening
7. ultherapy and thermage for external tightening
8. regular Venus legacy, exilis ultra, or inmode forma treatments with facials to maintain tightness
9. PDO novathreads or silhouette instalift cone threads for lifting and long-term collagen production
see an expert for a full evaluation and treatment plan based on your individual situation and goals.
Best, Dr. Emer

You’re both times as long since Violet and your message your muscle has regained its full strength.
your entire face looks different in the two pictures. I think there are other variables that you were not taking into consideration. These may be changes in weight?
I don’t think the Botox left you with a permanent deficit that can’t be explained by other factors.
I don’t think a mini facelift is the way to go in your case. You seem a bit young for that.
Probably working with volume restoration is your best option.
Best,
Mats Hagstrom MD