I was just checking my 1v1 ladder profile and with my game against grona it says:

grona • apex defeated hedja (expiration imminent)

I am used to it saying "expired" or saying when it was going to expire, such as "expires in 3 days". Does this just mean it will expire in the next few hours, the next day, the next week? I have never seen this before which is why I was interested.

Should mean it expires that day, not sure how often the ladder updates (every few hours?)

"The ladder updates once every other hour starting at midnight GMT, then 2am GMT, 4am GMT, etc. Each update, it updates ratings and rankings of all players and creates new ladder games. "