Don't really use addon skins myself but some people reported issues with outfitter caused by addonskins.
If you open the menu of outfitter from the charpane after the error you see half converted interface.
Only helping maintaining that addon and my lua ui skills are not good enough to know if outfitter does something wrong or purely caused by addon skins.
1x Interface/SharedXML/SharedUIPanelTemplates.lua:573: Action[SetPoint] failed because[Cannot anchor to a region dependent on it]: attempted from: OutfitterFrameTab2:SetPoint.
[string "=[C]"]: in function `SetPoint'
[string "@Interface/SharedXML/SharedUIPanelTemplates.lua"]:573: in function `PanelTemplates_AnchorTabs'
[string "@Interface/SharedXML/SharedUIPanelTemplates.lua"]:566: in function `PanelTemplates_SetNumTabs'
[string "@Interface/AddOns/Outfitter/Outfitter.lua"]:4701: in function `Function'
[string "@Interface/AddOns/Outfitter/Libraries/MC2SchedulerLib/MC2SchedulerLib.lua"]:242: in function `OnUpdate2'
[string "@Interface/AddOns/Outfitter/Libraries/MC2SchedulerLib/MC2SchedulerLib.lua"]:178: in function `OnUpdate'
[string "@Interface/AddOns/Outfitter/Libraries/MC2SchedulerLib/MC2SchedulerLib.lua"]:20: in function <...fitter/Libraries/MC2SchedulerLib/MC2SchedulerLib.lua:20>
Ah it's probably because I changed the buttons from left to right instead of right to left.
I couldn't get right to left to work anymore for the buttons in dragonflight with outfitter.
Don't really use addon skins myself but some people reported issues with outfitter caused by addonskins. If you open the menu of outfitter from the charpane after the error you see half converted interface. Only helping maintaining that addon and my lua ui skills are not good enough to know if outfitter does something wrong or purely caused by addon skins.