Please note, that the time on posts is different for all users. It depends on the timezone user selects in His/Her Profile > Account page.
The default timezone is based on the WordPress timezone. You can set the WordPress timezone in Dashboard > Settings > General admin page.
After each change of timezone if you want to see the difference immediately, you should delete WordPress cache (if you have a cache plugin), then go to Dashboard > Forums > Dashboard and delete wpForo cache clicking the [Delete All Cache] button.
We are all in the same timezone. The timestamp is showing time and dates from January 2020 before I had installed the plug in. I installed the plug in in mid April. So something is definitely wrong.
I just tested it again after messing around with different settings and it's working.