Penalty on excess contributions to 401(K) Account

In August, 2021 I raised the contribution election to my Pre tax 401(K) Account. Now, while preparing my 2021 Tax Return Turbo Tax calculated a penalty for excess contributions because my contributions exceeded the $7,000 limit. I am confused because when I received the confirmation letter from the Plan Administrator regarding the change in contribution rate it included a statement "Contribution limits for pre-tax contributions is $19,500 for 2021". My contributions for 2021 are well within that limit. Is the software wrong or am I entering something wrong?