I have documented the pain and struggles I’ve encountered when using the Quote Block in the post editor in the past and recently, I encountered the same pain and struggles again. This time, however, I discovered a workaround that will save future me a lot of hassle.
The temporary solution is to use a Classic Block and then use the Quote button within that block which essentially provides the functionality that was present in the Classic Editor. This method retains the formatting and pasting the text into a quote simply works. It’s not an impossible task that the current Quote Block is unable to accomplish.
I try not to use the Classic Block for anything but as I use the Quote Block fairly often, the frustration has proven too much. So thank you Classic Block for being there for me.