Okay, so he looks pretty good, though a little small for a 2-3 year old male, probably due to the bad UVB tube. I don't know where you live in the world, but in the United States the best UVB lights available are long tubes like the one you have, but the only adequate brand here that I'm aware of are the Reptisun 10.0 (never use the 5.0) T8 or better yet the T5 High-Output tubes. They come in several different lengths, 18", 24", 36", etc. With the Reptisun 10.0 tubes, the T8 is the weaker of the two, though it's totally adequate, but must be mounted inside the enclosure like yours is and absolutely cannot sit on top of a mesh lid or be obstructed by anything. It also must be mounted within 6"-8" of his main basking spot. The T8 must also be replaced once every 6 months at a minimum, as it stops emitting
UVB light at that point. In contrast, the Reptisun 10.0 T5HO UVB tube can be mounted on top of a mesh lid or inside the enclosure as long as it's within 11" of his main basking spot, and must be replaced once every year. So the Reptisun 10.0 T5HO UVB tube is definitely the best available in the US. The only issue you may have with the T5HO is that it requires a long, flourescent tube fixture that is rated for a T5 tube at 24 watts, so the fixture you have may not work for it, and you may need to upgrade the fixture as well. But it's a very good, long-term investment, I've been using the Reptisun 10.0 T5HO UVB tubes for almost 12 years with stellar results.
In the UK and Australia, the best UVB tubes available are made by Arcadia, the 12% Arcadia tube is what you want, do not go for the 10% Arcadia, it's not strong enough.
I did research your brand of UVB tube, and it's just as I thought, it's similar to the brands Zilla, All Living Things. and Reptile One. They are very cheap, Chinese-made UVB tubes that actually not only emit very little
UVB light to begin with, but they also stop emitting all
UVB light after a month or so, they just aren't good quality at all, and are only effective for a bearded dragon if they are mounted within 3-4" of their basking spot, which is nearly impossible to accomplish in most enclosures, and is a very dangerous risk to their eyes if you do mount them that close. Plus, they stop emitting appropriate strength and wavelength
UVB light very shortly after being turned on.
The other very important recommendation I would make to you is that you absolutely need to increase you "photoperiod", or the length of time your beardie is under both his bright white basking light and his
UVB light. If you have his lights on for only 10 hours a day (8 a.m. to 6 p.m.) he's not getting nearly enough of the already weak UVB and UVA light he has. His lights absolutely must be on for a minimum of 14 hours every single day. So if you turn your lights on at 8 a.m., you must leave them on until 10 p.m. at a minimum. Also, be sure that you're using only a bright white basking bulb, no colored bulbs at all, and that after you replace his UVB tube and potentially his basking bulb, you remeasure his basking spot (100-105 degrees), his Hot Side Ambient (88-93 degrees, and his Cool Side Ambient (75-80 degrees) with a digital probe thermometer or a temperature gun only, no stick-on thermometers that are usually off by up to 20 degrees, and cannot be used to measure the temperature of his basking spot but only ambient air temperatures.
He's done growing in length at 2 years, so he's a bit stunted but not horribly, so after you get him a vry good UVB tube that emits strong enough UVB and UVA light, and you increase his photoperiod from 10 hours a day to 14 hours a day, his appetite, activity level, shedding and brightness, etc. are all going to increase and he's going to be on his way to recovering from any MBD or Vitamin deficiencies he may be starting to suffer from. I would be sure to use a calcium powder that has D3 in it only for the next month or so, since he hasn't had any adequate
UVB light to help him manufacture his own vitamin D3, but after about a month under a good
UVB light and an increased photoperiod you can cut back to using calcium with D3 only once or twice a week, and use just plain calcium without D3 the rest of the week. I'd also up his multivitamin powder use to 4-5 days a week, using a good quality multivitamin for reptiles, like Herpavite.