@Extra I am having the same issue. Most of the news I see is new but I have news that is showing from 4 5 and 6 months ago as well. I have tried multiple different ways to format the config with the same problems everytime. Did you ever figure this out?
[23.01.2022 14:55.17.502] [ERROR] Error [ERR_REQUIRE_ESM]: require() of ES Module /home/pi/MagicMirror/node_modules/node-fetch/src/index.js from /home/pi/MagicMirror/modules/default/calendar/calendarfetcher.js not supported.
Instead change the require of index.js in /home/pi/MagicMirror/modules/default/calendar/calendarfetcher.js to a dynamic import() which is available in all CommonJS modules.
This is the wrong version of node-fetch that is installed on MM. You need to downgrade node-fetch to v2.6.1 or something earlier than v3 where the module was change to an ES module. I would uninstall node-fetch and check which module uses it and what specific version and install the correct version.