A power strip with ground fault LED. The room Earth GND connection at outlet may be faulty, try some other outlets with that same power strip in other areas throughout the house and observe the results, Then becomes a search and find via the Breaker box terminal control lever for any problematic rooms if more than one.
:An Example for locating possible faults without removing anything:
Lets say there are more than one outlet showing fault, then a breaker lever for that room or outlets is switched off in this event example, and lets say you may find in this example 3 or so outlets that have this fault and a single breaker is switched off, all the problematic outlets are now off in tandem (adjective) / all the noted outlets are now powered off, is a leaning solution to comprehending the fault is likely the breaker box area or that line is an add in with no link to Earth connected, If it is only one outlet, then the Earth wire may be loose not not exist per that outlet.
As stated GND fault is dangerous.
Notes The Breaker box contains dangerous voltages + currents via the MAIN breaker indicator, some can be from 100 Amps (older homes) to over 400 Amps easy, then from there the rails are split off via the secondary breakers to rooms, appliances and such.
If not familiar with High voltage, Would not advise on entering the casing to observe any potential faults there OR with the outlets, as I have no clue of your understanding of the Mains, as also my understanding is limited.
Overall recommend a quali tech.