When i go into group,raids or just log in achievements frame pop up and tries to compare my achievement with ppl in group or if i log in with my own char.

I think i can almost confirm that issue is with this addon since if i disable it comparing is gone.

Are you using windtools?

I suffer the same issue had to turnoff addon on each character

No . Windtools are part of elvui?I dont use elvui

I did erase saved variable for KAF and then this poped up as error
Message: ...ntFilter/Gui/WindowFrames/AchievementFrameHeader.lua line 228:
attempt to index field '?' (a nil value)
Debug:
[string "=(tail call)"]: ?
[string "=(tail call)"]: ?
[string "=[C]"]: ?
[string "@Interface/AddOns/Krowi_AchievementFilter/Gui/WindowFrames/AchievementFrameHeader.lua"]:228:
...ntFilter/Gui/WindowFrames/AchievementFrameHeader.lua:215
[string "=[C]"]: SetText()
[string "@Interface/AddOns/Blizzard_AchievementUI/Mainline/Blizzard_AchievementUI.lua"]:259:
...rd_AchievementUI/Mainline/Blizzard_AchievementUI.lua:257
[string "=[C]"]: ?
[string "=[C]"]: ?
[string "=[C]"]: ?
[string "=[C]"]: ?
[string "=[C]"]: Show()
[string "@Interface/AddOns/Krowi_AchievementFilter/Globals.lua"]:475: func()
[string "@Interface/AddOns/MRT/Inspect.lua"]:241:
Interface/AddOns/MRT/Inspect.lua:214
[string "@Interface/AddOns/MRT/Inspect.lua"]:671: func()
[string "@Interface/AddOns/MRT/core.lua"]:806:
Interface/AddOns/MRT/core.lua:795
Locals:
(*temporary) = 3.658000

MRT is https://www.curseforge.com/wow/addons/method-raid-tools
I tried switching off MRT and seems i dont get compare window on entering game as of this time.

Reason for me asking is this conversation: https://discord.com/channels/805554495253643315/1025422778658209863/1051014044192096266
And this: https://discord.com/channels/805554495253643315/1093256710493327410/1093256710493327410

I did bosses in tanaris and didnt get compare windows at all. So it seems KAF+MRT in combination does it. MRT has module raid inspect and that part that is possibly interacting with KAF. Also last few updates of MRT was about raid inspect.

If i disable MRT achievement filter in raid inspect don't see compare window when i log in.

Thank god I was going crazy. Thanks for the temporary fix!