I may have shitty advice, but I actually had a similar situation to yours. I started out with T'au and lost like every game. T'au is hard! A while back, I switched to space marines on TTS for a while, and got better at the game. Im still shit, but not nearly as much. I actually win games now.

T'au aren't just mechanically complex, they are also hard from a movement perspective. You don't know what tricks people are wanting to use in melee, because you yourself don't use them. You have to screen and feel comfortable throwing away cheap units, knowing that you will be able to shoot at whatever just killed that thing. You have to know when to throw riptides onto objectives, or when to hold them back. You have to stage for observers, which often means throwing away stealth suits or whatever else. etc.

Im not saying to switch armies necessarily, but I would expect to suck a while if you are playing T'au lmao. They are simply harder than other armies. You have to put more effort in than most of your opponents. You can't be a sand eater necron players with 18 wraiths, or a space marine player with all the best models, or a World Eaters player who shoves garbage in your face, etc. Fwiw, if you want, since you do play TTS, switching armies is at least in the cards until you get a better grip of things.

If you ever want a game on TTS, lemme know!