Thanks @JohnB5677 and @Mike9241 for your reply!
So the loss of $200 can be deducted in last tax year 2020, not defer to 2021, although the replacement shares are sold within 30 days too. and the loss of $300 in transaction #4 is not a wash-sale, so I can claim a total of $500 loss in the tax year 2020, are these correct?
I thought I need to re-purchase 10 shares of the same stock in year 2021, and then add $200 to the cost of 2021 purchases, and claim the loss in tax year 2021, it seems this is not necessary, right?
