Finally iOS latest update to 17.4.1 and 16.7.7 seem to have fixed this issue. Congratulations Apple, it only took 5 months. I have still not received a single reply to my bug reports, no helpful replies to all of my tries to get contact – all just saying they would be not the right one for this. There simply is no way to give feedback if all is just set up to calm people, feed them with standard replies, simulate a service that is actually not existing. Very annoying.

Just to make sure this topic / issue has not been fixed yet and still – more than ever – urgent to be fixed, because the Find My Network currently fully depends on iPhones / iPads with older iOS which are getting fewer every day. Let me repeat: iOS17 is not participating (actively as Finder Devices) in the Find My Network anymore. Thus the network getting weaker every day which will make all AirTags literally useless in just a few more weeks months. After weeks and months watching this, filing bug reports, contacting support, trying to raise attention without ANY response about the topic from Apple, I would like to invite everyone to test it yourself, prove the issue and file bug reports, ask for support to finally wake up Apple. The network already is MUCH worse than last year, this has to be fixed ASAP. Here is a simplified and quite easy way to test it yourself: get two iPhones with different AppleIDs (a friend?) and at least one AirTag, make sure there is internet bind the AirTag to one, let it be unknown to the other running iOS17 turn off bluetooth at the AirTag-iPhone, turn it on at the iOS17-iPhone (via settings, NOT quick options) take only the three devices to an area without anyone else interfering (rural) watch updates in Find My App on AirTag-iPhone: it will never change Explanation: your iOS17 iPhone is supposed to report the location of the AirTag to Apple's server. Somehow it doesn't. Or it does but the information is not stored on server. Or the server is not sending it back to the Find My app. All leading to the same effect: the network dying.

Apple's support fixed the problem. Thank you for your efforts!

Thank you @szymczyk, but there is no (+) button. I only see colorful buttons "Apps", "Artists", "Books", "Media", "Podcasts".