It looks pretty appropriate for the season to me. Yes, it loses its leaves - if in sufficient sun, these can turn some pretty dramatic shades of gold and orange before they fall but if in a lot of shade, the colors are much less intense.

The brown, dry leaves may be an indication that it is not getting enough water. That does not appear to be a very big container for that large a tree so frequent watering may be called for. You may also want to consider potting up to a larger container size this winter when the tree is dormant.

Southern California also has somewhat alkaline water sources, which are not favored by JM's. Water pH should be somwhere between 5.5 and 6.5. You might want to acidify your irrigation water slightly by adding some household vinegar to the watering can. 1 cup of vinegar per gallon of water.

Thank you so much for your information. I will look for a bigger pot to switch it to. And I will learn how to check the pH of my water. When I bought it, the tag stated "morning sun only" Can it take a little bit more than that?

Yes, green leaved maples can take a lot of sun. If you are close to the coast, they could likely stand all day sun - further inland I would protect from hot afternoon sun or any heat reflected off of walls, paving, etc.

Great. Thank you so much.