Thanks @steliosI did watch that from your other post I found the...

Thanks @stelios
I did watch that from your other post

I found the 18th update on Basel III implementation on BIS website released July 2020.

I see now where 28 June 2021 comes from. It's the implementation date for the EU and UK. Interestingly, the US is not until Jan 2022 and China has not set the date.

I wonder how this will play out in the period between July and December, or whether LBMA and others will get an extension to align the implementation with the US timeline