This looks like something from last year as this bus was scrapped under Ulmer Park. The old license kind of indicates it.
And there's a video of it last year with the same ads on the M4:
3834, 3887, 3970, 4119-4120, 4122, 4128, 4135, 4342, 4346, 4517, 4528, 4922, 4929, 5151, 6764, 6774 are being loaned to West Farms at this time. I wonder what's the deal with these loans as of late.
Getting the depot sticker doesn't always mean that the bus is assigned there on the long term. There have been scenarios where a bus gets a new depot sticker, only for it to be shipped back to its previous depot shortly afterwards.