Hm I have not heard about such an issue so far but I also don’t have as many UPS as you.
I see you holding a red cable which could be +. When I switch UPS batteries, I do it the same way as it’s recommended for car batteries to avoid sparks/arcs. Remove - (black) first, as it won’t spark/arc. Then remove + (red) as it can’t get a circuit closed any more, so also no spark/arc.
When plugging a car battery in, it’s the other way around. + (red) goes in first and only then you connect - (black) to avoid spark/arc for both connectors again that way.