@Skiboot
it is a known issue that 5G on S20 series does not work well with PM or Koodo, mainly because it was blocked on the OS level, an agreement between Telus and Samsung because both Koodo and PM did not have 5G support when S20 was introduced. Yes, PM and Koodo both supporting 5G but it is too late and Samsung no longer update the OS to allow the phone to use 5G on PM
But even with you connected on LTE, your speed shoudl still be as good as you are on 5G network (close to 200Mbos) Please try "Reset All networks" on your phone first, and also test the phone in different area
https://productioncommunity.publicmobile.ca/t5/Get-Support/Samsung-s20-5G/m-p/1043676#M728790
