The OSM-Link-Validator (1) might be interesting for you. A fellow mapper form Munich uses ist to regularly check for broken links.

(1) https://codeberg.org/strubbl/osm-link-validator

What’s interesting to know about class:bicycle in Munich is, that it’s basically an undocumented import by MunichWays (a division of the Green City association). I’m also not happy with every single road classification and the addition to OSM was a bit chaotic due to some beginners mistakes, people sometimes not responding to changeset comments and sometimes importing outdated data.

But on the other hand, MunichWays did a lot of detail work for classifying roads in Munich and the data is way easier to access for data consumers, now that it was added to the OSM database.

Another addition: A mass closure of Iranian notes was done a few months ago: https://resultmaps.neis-one.org/osm-notes-country?c=Iran

To me it looks like this is the problem: https://github.com/osmlab/onosm.org/issues/127

Looks like there already is a bot that closes useless notes (see: osm.org/note/3969523)