Did you check an aliquot of the undigested vector prep on a gel? I suspect the problem is with a poor quality miniprep and that you won't see a nice supercoil band when you run out uncut plasmid. I would just start again, perhaps modifying the bug growth conditions if it's a low copy number plasmid.

Smearing on an agarose gel after digestion usually indicates incomplete or nonspecific cleavage of DNA. It may occur due to excess enzyme, star activity (non-specific cuts), or degraded DNA. Improper buffer conditions or contamination with nucleases can also cause DNA breakdown. Overloading DNA into wells may lead to streaking instead of sharp bands. Ensuring fresh DNA, correct buffer, optimal enzyme concentration, and proper incubation can minimize smearing.

I agree with other commentors. It looks like inefficient digestion of the vector. I know XbaI is methylation sensitive, and I've had problems digesting backbones with XbaI for this reason. Double check that your XbaI sites are not blocked by methylation.

Is XbaI affected by methylation? | NEB

10-15ug is way too high for your 50uL reaction. I routinely used NEB REs and if not mistaken they did mentioned that for 50uL rxn,

I agree with other commentors. And I think that enzyme concentration too high for night digestion. I use 0,2 µL of each enzyme for 10–15 µg of vector DNA usually.

I have to disagree with some of the comments, the smear you are seeing is a smear and not the result of incomplete digestion. I think your plasmid mini prep is not good but to confirm then as suggested above, run some uncut plasmid on a gel. Secondly, I'm not sure how much of your digest is on the gel, but you mention you digested 10-15 ug of plasmid, however there is probably less than 1ug on that gel. So I think your quantification is not accurate. Lastly you don't need to do an overnight digestion. Most of the time restriction enzymes come as 10-20 units (or more) per microliter, so even if you did have 10ug of plasmid, the digestion would be done in less than an hour.