Christians are instructed to fellowship with other believers.
Heb 10:25 (NIV) not giving up meeting together, as some are in the habit of doing, but encouraging one another--and all the more as you see the Day approaching.
The recipients of the letter of Hebrews were being persecuted for their faith. Maybe some had stopped fellowshipping because of their fear of persecution and possible death.
Many have stopped fellowshipping today because of their fear of infection and possible death by a virus. Even when there are no restrictions or eased restrictions they don’t fellowship.