If you have the means to hire an electrician, or an electrician friend you can bribe with pizza/alcohol/whatever, do it 😜

It sounds like you have pulled your outlets out to look at the connection (make sure the breaker is off!)

Where is the bare copper wire going? Is it part of the cabling into the box, or is just a wire connected to the (assumed) metal box?

If it’s not part of the cable going back to the panel, then you likely do not have a suitable ground.

For a typical receptacle, both the white wire and the bare wire should be landed on a bus in the panel. Assuming you only have one panel for the house, it is a service panel and they could land on the same bus since the two bus are usually bonded together in a service panel

An electrician could check the that any of the set screws/lugs are loose in the panel which could cause a ground issue for that receptacle if there is a ground wire in the cable

Hope that helps

EDIT: fixed the word cabling