The best way to find out is to ask a friend to either use their trainer OR hook up a friend's bike with an on-bike meter to a dumb fluid trainer or mag trainer then make a go at it.
Given the distances and mileages you claim, I don't see it feasible at all for the power to be that low. To go those distances and that speed for that one ride you mention at your weight..........it almost seems like the trainer might be reading roughly half.
I could totally see a lifter's 5s sprint power being just a hair over 1000w, with your 500w number being half.
Try to find a willing friend, then you'll know! Some folks online claim the sensor inside reading speed was bad within a week or so and led to low power readings. There was a new power supply brick for newer units around Fall 2019 also. The older bricks would fry the unit somehow. Need to make sure you don't have that issue also.
Good luck.