Shield of Solitude originally had a unique, stronger Resist Magic effect different from the game's normal Resist Magic effect that as such could be uniquely disenchanted. I always felt that this enchantment was the main quest reward rather than the shield itself, so I wasn't a big fan of the unofficial patch changing the shields enchantment to be a stronger version of the same resist magic enchantment that every other item gets to have.

To clarify, the unofficial patch did not lower the total magic resistance given by the shield, they changed the base effect used for the shield. Originally you could disenchant the shield to learn it's unique resist magic effect which was stronger than the resist magic effect on any other item. (The reason why this might be considered a bug is  because it will allow you to know two separate resist magic enchantments to enchant items with, this could be used to enchant one item with two variations of the resist magic enchantment with the 'Extra Effect' perk)

I'm not trying to debate whether or not this change was justified, I just personally didn't like it so I made a mod to undo this change and decided to share it. This is a simple ESP file, so just drop it into either nexus mod manager or the data folder and enable the plugin.