Why do you believe this to be true? Why do you think Tesla's lead is slipping?On utility scale I see no evidence that Tesla is building a stronger lead, and the balance of probability is that the lead they had is slipping.
In my mind, Tesla has two advantages with its Megapack product:
1. Lanthrop and future factories. The factory is the product. With unlimited demand, the opportunity for profit is only limited by factory output. Is anyone outside of China building utility scale storage faster than Tesla?
2. Available batteries. Does anyone outside China have access to more cells at a lower cost?
So Tesla owns the market in the Western world and China owns the market in the Eastern world. This is a very good position to be in and it seems to me that it's the opposite of "slipping".
I'd love to know why I'm wrong.