iCloud Please help - Messages almost 200GB in iCloud - how do I delete?

[ChromeCrescendo]

Up until last week, I had been using the 50GB iCloud plan (I had never come close to filling it up)

Knowing I was going to be needed more storage for various music projects, I upgraded to the 200GB plan.

Just today, I received a notification that my iCloud was almost full and, upon checking, saw that Messages was using almost the entirety of the 200GB (see photos) -- how is this possible considering I never came close to using the 50GB plan I previously had? I only have about 10 conversations open in iMessage across my devices

It seems the only way I can delete all of this data is to disable iCloud but, then I will not see all my messages on all my devices -- anyone else running into this? is there a way to fix this?

This is the iPhone storage for messages:

 

[Sheepish-Lord]

How many macOS devices do you have using iMessage? MacOS iMessage loves to important very old stuff and doesn’t sync properly like iOS or iPadOS.

Look at the iMessage app on one of your macOS devices and you’ll probably see insanely old messages.