Character limit in SharePoint doc library columns.

I have three identical doc libraries on three SharePoint sites. They all have the same columns, a few of them being "Multiple lines of text". 

In the original doc library there is no limit* to how much text can go in those "Multiple lines of text" columns, but in the two copies of this doc library these columns are limited to 255 characters. 

I have a Power Automate flow which saves documents to these libraries and puts info into those columns based on answers to a Microsoft form. Its one flow that will save the document and update the properties to the correct document library based on an answer to a question on the form. When saving to one library, there is never an issue with how much someone types into the associated question on the form but when saving to either of the other two libraries it will fail if they type more than 255 characters. 

I'm at a loss here. These three libraries are carbon copies of each other as far as I can tell, so why is there a 255 character limit for the columns in two of the libraries but not in the first one I created for this process?