Did you double-check SmartSwitch to ensure the count is 2673?
Did you ensure the S21 has enough storage space?
Good evening @useryBW2p3CcpJ I hope you're doing well
I'm sorry to hear that all the data you attempted to transfer via Smart Switch did not transfer.
Regarding text messages from my experience; Smart switch will only allow up to two to three years of older texts transfered to a new device.
Photos and videos and all other data have to be transfered in the moment so there wouldn't be away to transfer data that isn't showing up from an external device.
Try using SMS backup and restore. It transfers more varieties of data than Smart Switch. I had to use SMS B&R in order to get all my text messages transferred to my new phone because Smart Switch does not recognize RCS messages in it's programming.