Batteries are rated for a certain continuous current draw, and if you try drawing too much, you're going to have a bad time. Some of these flashlights can draw a ridiculous amount of power, and if you're putting a cheap knockoff 18650 in it with no internal protections, it's not going to be a fun time.
It's the same issue people had with vapes exploding. The original included batteries might only be rated for a continuous draw of say, 10A, and they're adding these crazy high wattage coils trying to get 30A from them.
I have a few pairs of pants with holes in the pocket from a Wurkkos FC12 I got on Amazon for about $35. It's bright as hell, has a built in USB-C charger, and goesnwith me pretty much everywhere.
Wurkos fc11 I think on Amazon. Fantastic. For these crazy lights you mainly just need nice high draw 18650s from a reputable store online and a nice 18650 charger. I had a cheapo charger from Amazon that screwed 2 batteries and they wouldn't cool down, hot to the touch for hours. A bit concerning lol