This isn't so much a v8 issue as its in v7 too but its something you should change in the next upcoming version.
WHMCS for a long time has offered "Ban IP" when viewing an order.
When you click Ban its always used 31/12/2020 23:59 as the ban expiry date, this means throughout WHMCS history all orders banned for everyone will automatically unban 31/12/2020 this year. (see attached example)
Today on my test Beta3 install i banned an order and it still uses 31st Dec 2020 which is only 4 months from now.
can WHMCS change the logic so its something the administrator can configure, I think a good default for Ban IP is 1 year, for example if i banned an IP today it would unban 1 year today rather than all blocks be given the same date -- but the admin should be able to configure this as some may want block for 2yrs, 10yrs etc.
Based on the current system if it doesn't change if i blocked an IP on 1st Jan 2021 its ban expiry date would be in the past.
I did log this as a support ticket earlier this year but was told it won't be changed! It needs changing.