Ran a weekly pacman -Syu to get some update going. But when i booted back, lots of system icons and text are just broken. Rebooting, downgrading packages and checking font settings didn’t do anything to fix it and that only happened after updating, login screen had stripes running down too.
System was a Thinkpad T420 with the Cinnamon DE. This was on x11 but running Wayland didn’t change anything.
Hi and welcome to the community 
Did you make any changes to the theme, icon set, fonts or anything similar?
I fired up a test VM with EOS Cinnamon, made a few changes, did an update.
Everything seems to be normal.
Perhaps try this:
Go to Settings >> Font Selection
Under Hinting and Antialiasing change the settings from whatever current default you have to None for both of them.
Minimize or click away from settings to see if the change was registered. If yes, then change them back to what you had.
Does this resolve the issue?
Welcome to the forum! 
From your screenshot the text labels are scrambled system-wide — in Nemo and FreeTube both — which points to a fontconfig issue after the update. The icon rendering might be affected too, hard to tell.
First try refreshing the fontconfig cache:
fc-cache -fv
Then log out and back in.
If that doesn’t help, also run:
gtk-update-icon-cache -f -t /usr/share/icons/hicolor
Can you share the output of:
pacman -Dk
This will tell us if any packages ended up with broken dependencies after the upgrade.