the error logs say:

cat error.log.2022-09-19 
time="2022-09-19 01:34:17.575725" level=error msg="Failed Initial Syncing Room" RoomID="!uokpefhixlnlbsdxsg:f-droid.org" error="contents=[123 34 101 114 114 99 111 100 101 34 58 34 77 95 70 79 82 66 73 68 68 69 78 34 44 34 101 114 114 111 114 34 58 34 85 115 101 114 32 64 115 116 97 116 105 99 58 102 45 100 114 111 105 100 46 111 114 103 32 110 111 116 32 105 110 32 114 111 111 109 32 33 117 111 107 112 101 102 104 105 120 108 110 108 98 115 100 120 115 103 58 102 45 100 114 111 105 100 46 111 114 103 44 32 97 110 100 32 114 111 111 109 32 112 114 101 118 105 101 119 115 32 97 114 101 32 100 105 115 97 98 108 101 100 34 125] msg=Failed to GET JSON to /_matrix/client/r0/rooms/!uokpefhixlnlbsdxsg:f-droid.org/initialSync code=403 wrapped=M_FORBIDDEN: User @static:f-droid.org not in room !uokpefhixlnlbsdxsg:f-droid.org, and room previews are disabled" worker=23