Small gaps go missing for α μ ι (alpha mu and iota) in parts of the 1000 wght + 144 opsz design space

This is wdth 25 -

The letters are α μ ι (alpha mu and iota). Tau is shown as the example of the gap I was expecting

At wdth 100 things rearrange with only mu surprising me in spacing terms.

At wdth 151 things rearrange again and the same set that worried me at wdth 15 does again.