well pla temp is a little hot for such a low print speed.
200c is better for 50mm/s

But it looks like a period of underextrusion.
Could have been a thinner section of the filament, partial clog that cleared itself, dodgy slicing (less likely).
Feeding issues, tight filament reels can cause this.
If you had adelta then it could also have been bowden tube configuration. But you're not, so ignore that bit :-)

Basically I'd say it's a filament issue. try a different brand or colour.
If you get the same problem in the same area with different filament, then we can start to look at other possibilities.