The light came with an alternate mount that screws on to the handlebar but it makes taking the light off more annoying, and obviously removes the ability to freely put the light on different bikes
I was hoping this design was universal but none of the straps I'm seeing online have the screw hole. Well, there is one very similar strap but I'd have to pay 13€ postage on a 5€ item which offends me on a spiritual level
Speaking from experience here; your problem isn't gonna be the strap, it that it fits to the screw interface on all points. While they all look 99% similar, they're not, unless this is a Lezyne or something.
I'd advise you to buy a generic "flashlight bicycle mount" from wherever, something like this;
Has the added bonus points for if it holds up and your light doesn't you can also just use it for the next one.
Alternatively glue and ziptie a garmin quarter lock mount (knockoff, obviously, but using that standard) to it and get yourself a female receiver to attach to your bikes handlebars. They're all ubiqioutous and therefore well cheap.
I think it might be a Lezyne, it has almost the same design as mine but slightly longer and thinner.
But yeah, those flashlight mounts will easily do the job, and you can find them super cheap.
It's not a Lezyne (searching for the brand of the light itself I only get Finnish/Nordic results so it's probably a design licensed off to a local company), but the very similar looking replacements I found were Lezyne ones. The only problem is that the postage fees for the straps are stupidly high in proportion to the actual price of the item. I'd pay 5 euros for one but not 5 + 13 euros. That's just nuts when I can get shit mailed from China for 3€ or free
They probably just copied it, there is only so many ways you to skin a cat and all.
I just wish someone in China had copied it and put it on Ali