It's not rooted after the update to 8.1.
OK, it looks that my problem is specific, so I should probably flash again my Mars. So, this morning I decided to download the firmware again and surprise, nobody on the download page:
https://mega.nz/file/uJ5hQKzR#WVI-wM...CesuLIQk6klFVg , the file is missing. Does this mean that they found a problem with this firmware version and withdrew it?