When I copy from a card's view mode and paste it somewhere it has a bunch of spans which can mess things up.
When I paste from a URL copied from another card's arrow link to the TinyMCE editor the link does not paste at all. I would expect it to paste, but to convert the link to the shortest form possible, taking out the server name if I pasted from and to the same server, leaving me with a /relativelink
(copied from improve pasting in from various sources)
Bullet point list (and probly numbered lists?) formatting is lost (after saving) when pasting in from EtherPad.
Lots of issues with Word, and copy-and-pasting from browser pages.
improve copy and paste experience+discussed in support tickets
improve copy and paste experience+relevant user stories