Capitial gain from mutual fund.

I have a mutual fund from Vanguard.  I got a consolidated 1099, entered all the info from 1099 div to TT.   Vanguard 1099 shows the details of capital gain distribution, where the long term capital gain is $10,000. I did not buy nor sell the mutual fund.  I think this LT gain should be taken care of in the TT.  How do I enter this LT capital gain in skedule D, where I do not have a base price since I did not sell nor buy in 2021.  TT looks like this treating as short term (normal income).