Missing Emails Across Multiple Accounts on iPhone 12 Pro Max with iOS 16.5.1

I'm using an iPhone 12 Pro Max that's currently running the latest iOS 16.5.1.

This morning, I was surprised to find six months' worth of emails mysteriously missing from all of my email accounts integrated with the Mail app. Initially, I suspected it might be an issue specific to Yahoo, but on checking my iCloud and Gmail accounts, I found the same issue: half a year of both incoming and outgoing emails had vanished.

To clarify, these emails were not moved to another folder nor were they in the trash folder. Furthermore, I have two-factor authentication activated for my iCloud, Yahoo, and Gmail accounts, and each one has a unique password for added security.

While trying to recollect any potential triggers for this, I remembered that I saw blue dots next to multiple emails last night before sleeping, indicating that they were selected. Sometimes I use this feature to clear out spam emails and on occasions, have to switch apps midway, intending to complete the deletion later.

Could it be possible that I unintentionally caused this massive deletion by leaving the emails selected? However, I find it hard to believe that this could result in the permanent erasure of six months' worth of emails across multiple accounts.

On a side note, I should mention that I also use the Gmail and Google Calendar apps for my work email accounts. Interestingly, the emails in these accounts remained unaffected by this situation.

I'm really puzzled and concerned about this issue. Could this be a software problem, or possibly the work of a rogue app installed on my phone? Any insights or suggestions would be highly appreciated.