It's my personal observations that in some engines, fan blades are connected to each other by a circumferential-running wire. More modern-looking fan blades seem to not have these wires. What motivates this engineering difference?
This trend is mainly driven by more advanced material and better aero and structural design of fan blades.
In earlier designs, fan has many blades and are fairly heavy (made of titanium-based alloys). They are prone to vibration either from an external source (unsteady wind that blow over) with a lack of damping, or from within itself (an inherent instability called flutter). Those wires (called shrouds or snubbers) are used to connect the blades, make them stiffer, provide support and damping to reduce the risk of excessive vibration, but this is at the cost of interrupting the air inflow, reducing fan efficiency, and adding weight.
An example is CFM56, https://www.cfmaeroengines.com/engines/cfm56/
Some engines have not one, but two of these snubber rings, e.g. Pratt & Whitney JT9D.
More current designs use lighter but also stronger materials that provide more damping to the blades. The blades can also afford to become bigger (wider in chord) without adding too much weight, which helps to largely eliminate the flutter risk. This makes the shrouds obsolete.
An example is the GE90 with composite fan blades: https://www.geaviation.com/commercial/engines/ge90-engine
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