Hey there, I know this is old but I am also experiencing this issue as of 3/17/2025. I have no UISizeConstraint instances in my experience at all, so this is an odd error.
Before, trying to set MinSize > MaxSize would ignore the attempt and print this unhelpful warning. Properties had to be set in a specific order to avoid this. Roblox’s internal code often sets properties from a table, which creates a randomized order. This is why the warning could be printed even when your experience used no UISizeConstraints.
Now, the warning message and the restriction have both been removed. If MinSize > MaxSize, then the UISizeConstraint will be ignored.