I am copying my files from a Mac book pro to easy store and it is taking over 20 hours. Is this normal?

It depends on your Mac and your drive. Older Macs with mechanical hard drives are too slow. Also your drive might be a USB 2 model which is again very slow. Finally, transferring something that has many folders within folders within folders could severely affect transfer time.

When I tried to transfer 150GB from an old MacBook with mechanical hard drive to a new one with SDD it took me some ridiculously long time but don't remember exactly how much.

Possibly, depending on how it’s connected. There should be a progress bar to confirm the transfer is ongoing, if it is you’re fine.