Thanks again.
I have searched a bit more. Basically the changes which are made are mentioned here (I basically hit almost the right day for the change time 
):
This changes are made for android compatiblity. These changes seem to result in problems for some test pages. To avoid that problems it seems to be possible to switch back to the old short version of the chains but that will result in problems with android devices. If some mailsevers will act like the test pages that could be problematic because in this case sent mail is maybe not accepted (but this is just an assumption but if two test pages are working like that it could be possible that some mail servers will also react in the same way).
In certbot the --preferred-chain seems to be the option for getting the short version. I have not tried it but this is not really a good option if android compatibility is partially lost via doing this.