Aww that’s such a shame! Niantic can be a bit inconsistent with decisions on parks and green spaces with no signs.
I hope you can be a bit inventive and try to find a way to frame a main picture that shows its more distinctive, and get a success from it
@elijustrying linked one of my successes and here are 2 other recent signless entrances. One was accepted on appeal and the other was rejected but overturned on this forum so now shows as an acceptance 
