Recently there was bug in Gmail which accidentally delete emails and marked as spam while applying those actions to other emails. This bug was recently fixed on software update which did not affect all users and it is only some platforms. It is not sure that how many users get affected and the company announces the users to check the emails in Spam and Trash folder to have look between January 12th to January 21 st which was be mistakenly marked and moved due to the bug.
The verge reports about the issue to check the emails in spam and trash folder before February which you can find some missing emails due to the bug. Recently Google services were down including Hangout and Google Plus last week for about 25 minutes and it is calculated about 10 percent of users was affected.