As you may already know, Exchange Online has a specific archive feature to automatically expand the archive limit.

Well, starting November 1st, 2021 the auto-expand archive capability will no longer be able to provide unlimited storage as it used too – even if you had to go through a support request to expand the storage when the archive reached 1.5 Tb.

Starting November 1st, the hard limit for an online archive will be 1.5 Tb and you will not be able to request extension.

There will be no impact for online archives which have already reached the 1.5 Tb and have been already extended.