Your garden is not stuck in a time warp; it is constantly evolving. Trees grow and create more shade … and also dry out the soil. Since you began mulching five years ago, the soil underneath has become richer and more water retentive. Your neighbor’s irrigation system that seems to go off every night and sprays water in all the wrong directions is making the part of your lot right next to the fence much moister than it used to be, etc.
The easiest thing to do is not to try to combat these changes (bringing your neighbors to court for “loss of use” of your property is not a good idea!), but instead to follow them. Move the vegetable garden that is becoming less and less productive because of the shade to a sunnier spot, remove the yarrow that prefers poor, dry soil and now flops because the mulch has enriched the soil and replace it with astilbes that will love the richer, moister conditions, put in plants that like boggy conditions near the now soggy property line, etc.
When conditions change, the plants have to change too: learn to accept this fact and gardening will be so much easier.