Slides on .22LR pistols tend to be made of either very thin carbon steel, aluminun alloy, or a zinc alloy such as ZAMAK, but regardless of which material it is, they all tend to crack in the event of a catastrophic case blowout. In the case of the Glock 44, however, the slide is made of mostly polymer, with steel reinforcements in key stress areas.
Granted that Glock isn't the first to attempt this, as the Kel-Tec PMR-30 also has a polymer slide with steel reinforcements, is chambered in the more powerful .22WMR cartridge, and has been on the market since 2011 without any such issues occurring that I'm aware of, but it's possible that Glock simply didn't reinforce the slide well enough.
That being said, I'm curious if this is like the Glock 22 (i.e. the first .40cal Glock) all over again, with poor chamber support resulting in case blowouts on High Velocity .22LR ammo.
Or this could all just be a case of someone bubbaing up their Glock 44, cracking the slide by clamping it too tightly in a vice, then posting it online pretending that it's the fault of the gun itself. Time will tell.