@vincentleo How often are you training your biceps?
I ask as hitting three sets of 10 once per week is not that much volume and will certainly see you plateau at some point. Perhaps at 10kg.
If you want to get better at bicep curls, then do more bicep curls.
In practice this would mean doing them or a variation of them every session to maximise the volume you can pack in a given week.
There will be a sweet spot where too much volume in one session makes you tired meaning you do less the next, lowering your overall volume. If you can find the sweet spot then this is your Maximum Recovery Volume (MRV).
The above advice assumes your sleep and diet are on point. Have poor sleep or diet and the MRV you can handle will drop.
Also another tip, you can get stronger at bicep curls by doing other exercises too. For example pull up and chin up variations will still use biceps to some degree. So programming those in will act to increase the volume on that muscle group. Even bent over rows use your biceps, though to a lesser degree. So you may want to focus on overall training volume, and ensure your program is well rounded, rather than measuring only bicep volume.
Edit: also if your goal is arm size, then also train triceps. These are a much larger muscle group than biceps.