In our daily working hours, during changing of tags from some others, ALL orders were selected so now the tag of "Ready-to-ship" is being added in ALL of the orders starting from the beginning of the orders till the very latest order. Is there any way this process can be stopped at your end or halted?
I don't think there's a way to stop a batch tag update, I've never seen a way to do this.
I work a lot with order tagging (lead developer of Order Automator), we have functions to adjust tags on all past orders according to the order data... but you might not need that, for example if you're using that tag to indicate items that are ready to be shipped / fulfilled, then it sounds like you could just run a batch update in Shopify to remove that tag from all orders, and then add it back for the orders that actually need to be shipped.
If you need help with that feel free to message me and I'll try to help you get that organized.