You get so many calls from spammers and scammers, you turn off the ringer and just let things go to voice mail. Nobody answers their phone these days unless someone pre-arranges a call or messages first and then escalates it to a voice call. Phone fatigue.
So much spam and ham in e-mail that you turn off notifications and just occasionally go check your e-mail to find the 4 things of interest and delete the other 7000. Then wonder if maybe you overlooked and deleted an important one. E-mail fatigue.
You get so much junk mail, medical bills that say 'this is not a bill', mailings from places where you've selected e-statements and e-billing only yet they keep mailing - that eventually you stop bothering and it all just piles up on the counter. Until one day you go through it all, find a refund check from the IRS, and rush out to deposit it before it goes stale. Junk mail fatigue.
You go to the store to get X, but there are 47 varieties of X to choose from so you end up deciding you don't want it that bad after all and don't end up getting it. Decision fatigue.
The description of social media fatigue fits right in. With all that rapid attention switching, it gets hard to focus on anything for any length of time. Your mind starts craving a feed of constant stimulus, but it's exhausting. Attention fatigue.
The idea of Quiet with a capital Q is a good way to relax and recover from all that fatigue. My favorite is to take an actual physical book outside into nature and read for awhile, where the only distractions are birds, chipmunks, and butterflies. Unfortunately that doesn't work so well during winter when it's below freezing out, but at least there's still bathtime.