Apple Mail Search malfunction

On my iPhone, using the Search bar for anything in Apple Mail app brings up stuff from 2013 or 2016 - random years, actually - at the top of the list, the results are NOT in chronological order, and the results are incomplete. This does not happen when I go straight to iCloud from my @me dot com account, nor does it happen when I use Google Mail to check my @gmail dot com account. ONLY the Mail app on my iPhone malfunctions in this way. iOS 18.2.1 on iPhone12 ProMax. This has been happening for months. Turned iPhone off, restarted at Apple Store in Honolulu, cleared up for a couple of weeks, problem returned with last and previous update. Cleaned up old emails. Restarted. This is a serious malfunction.