There’s kydex and then there’s kydex and I would always reccomend a holster that is pistol specific , the “universal” options are always a compromise and are usually the least secure .
first up , make sure it is kydex , not just molded plastic , most proper kydex holsters will also have a tension adjuster ( nuts and bolts with rubber in between ! )
Also bear in mind most proper holsters are sized for the genuine pistol and light , airsoft pistols and clone lights can sometimes be out of spec and again cause fitting issues .
for me , for a light bearing holster it’s Safariland , for simple pistol only it’s either a genuine BHI Serpa or leather pancake style ( BHI / Galco )
Ive had a couple of deadly customs kydex holsters and tbh wasn’t impressed , one didn’t fit the pistol and light it advertised at all , the other just didn’t have enough retention adjustment and was a poor fit around some of the controls .
these are just my opinions / experiences , others will vary .