Rakuten Growth NISA allows me to exceed limits, is that normal?

Hi all,

I was just setting up the two NISA accounts on Rakuten Securities.
While Tsumitate has strict limits to not exceed the monthly or yearly allowance, the growth NISA shows no maximum limits. It allows to input monthly amounts of 1,000,000 and bonus amounts such as 900,000,000 yen, which greatly exceed the yearly limit, without any notice of doing so.
I contacted support and they said that after inputting the confirmation pin it would show that I'm exceeding the limit, but it actually doesn't, it just lets me set whatever amount and it accepts it.

Is that normal? Does it mean some amount will be tax-free and some will not? There's no obvious indication where the division happens. Any insight is appreciated.