4TB 2.5" portable drive will be SMR which will affect write performance, but after checking your original post you had issues with read speed.
Do you have any reallocated sectors in CrystalDiskInfo after formatting it and writing new data to it?
I have 0 reallocated sector count
The other 2 haven't changed and are still Read error rate is Red and data for it say 18371 / Current Pending Sector Count for data says 19