It’s a complete non-issue for starlink-sized objects at that altitude.

Yeah. The mass and altitude are too low.

The thing with Kessler Syndrome is that collisions create debris, which cascades with more collisions, until there’s too much debris. But each collision actually results in the loss of kinetic energy or gravitational potential energy overall, so that the subsequent pieces are less energetic and/or less massive. Start with enough mass and enough altitude, and you’ve got a real problem where it can cascade many, many times. But with smaller objects at low altitude, and there’s just not enough energy to cause a runaway reaction.