Users have been complaining to Opera to lift the block since it was added, but Opera has not done anything. That folder is not for unpacked extensions and Opera will remove them. (Do not put the Tampermonkey folder in Opera's 'Extensions' folder in Opera's profile folder. Then, in Opera, goto the URL opera://extensions, turn on developer mode, click 'load unpacked, and point it to the Tampermonkey folder. Then, edit manifest.json in the folder and remove both the 'key' and the update_url objects (the name, value, and trailing comma for each). Then, rename the '4.16.1_0' folder to 'Tampermonkey. If you want to run the regular version in Opera, install it in Chrome and copy the 'Extensions/dhdgffkkebhmkfjojejmpbldmpobfkfo/4.16.1_0' folder in the Chrome profile folder to your home folder on your OS. Only the ID for the regular version of Tampermonkey is blocked. (Browsers have more protection for automatically-installed extensions now though.) Opera chose to block it a long time ago because malware was automatically installing the extension and abusing it to run malicious scripts. Opera purposely blocks it by the extension's ID dhdgffkkebhmkfjojejmpbldmpobfkfo.
