Extrusion/Retraction speeds: aka E-speed
turn up your ex & re speeds speed from to 7 or 8 (always keep E-speed "how fast filament moves" and E-move "how much filament moves" at the same number setting) ...eye have best results at 7 move & 7 speed.
210 is low! may be causing your string issue! to explain what you are seeing...
...the plastic did not melt enough so that when a slow retraction happens "at E-speed & E-move set to 5, it fails to break the plastic clean off it's almost melted tail aka stringy crap. "lack of melt scenario"
... you need to adjust E-speed and E-move to 7 or 8 and change the PLA temp to 220 so that heated nozzle can melt the plan enough, and the retraction can happen faster (extraction speed must also happen at the same new speed in order to keep up with the higher retraction speed) this will allow the head continue it's path "clean" without dragging a piece of un-melted plastic, which won't break off because it has not yet reached the proper melting point for breakage upon retraction. so faster Emove and Esopeed and temp at 220 > bed is good at 60 ...if you notice bottom area warps at 60, bring it down to 55 > the perfect spot for pla.
@KrisJEC posted this hole back why-buying-quality-filament-matters
most filaments will behave differently so choose wisely and rest assured your prints will shine bright.
i use to buy PLA but now eye buy PHA from meltinc3d.com in Miami Florida, low in cost and the best material in the world if you ask me.. quite smooth, comes in may many bright cool colors and glows.