I had just completed a pet battle prior to to flying. Pressing soar cause the following error. Trid again with just the following mod: bug grabber, rematch, pet battle scripts and buyemall and was not able to recreate the issue.

1x [ADDON_ACTION_FORBIDDEN] AddOn 'BuyEmAll' tried to call the protected function 'UseAction()'.
[string "@!BugGrabber/BugGrabber.lua"]:485: in function <!BugGrabber/BugGrabber.lua:485>
[string "=[C]"]: in function UseAction' [string "@Blizzard_FrameXML/Mainline/SecureTemplates.lua"]:342: in function handler'
[string "@Blizzard_FrameXML/Mainline/SecureTemplates.lua"]:667: in function <...ddOns/Blizzard_FrameXML/Mainline/SecureTemplates.lua:649>
[string "@Blizzard_FrameXML/Mainline/SecureTemplates.lua"]:681: in function <...ddOns/Blizzard_FrameXML/Mainline/SecureTemplates.lua:674>
[string "@Blizzard_FrameXML/Mainline/SecureTemplates.lua"]:723: in function SecureActionButton_OnClick' [string "@Blizzard_ActionBar/Mainline/ActionButton.lua"]:100: in function TryUseActionButton'
[string "@Blizzard_ActionBar/Mainline/ActionButton.lua"]:135: in function `ActionButtonDown'
[string "ACTIONBUTTON2"]:2: in function <[string "ACTIONBUTTON2"]:1>

Locals:
_ = Frame {
}
event = "ADDON_ACTION_FORBIDDEN"
events =

Hey, I have a suspicion that this is Blizzard's errors being weird again. BuyEmAll does not do anything with action buttons, and doesn't change anything in the default UI, which make sme think it's probably another addon that is causing this issue.

Can you consistently reproduce this with a pet battle?
If yes, can you try disabling all your addons except for BuyEmAll, and then see if the issue persists?

I too get the same problems since today, hasn't been happening earlier

1x [ADDON_ACTION_BLOCKED] AddOn 'BuyEmAll' tried to call the protected function 'MultiBarBottomRightButton5:SetAttribute()'.
[string "@!BugGrabber/BugGrabber.lua"]:485: in function <!BugGrabber/BugGrabber.lua:485>
[string "=[C]"]: in function `SetAttribute'
[string "@Blizzard_ActionBar/Mainline/ActionButton.lua"]:488: in function `UpdatePressAndHoldAction'
[string "@Blizzard_ActionBar/Mainline/ActionButton.lua"]:554: in function `Update'
[string "@Blizzard_ActionBar/Mainline/ActionButton.lua"]:1078: in function `OnEvent'
[string "@Blizzard_ActionBar/Mainline/ActionButton.lua"]:302: in function <Blizzard_ActionBar/Mainline/ActionButton.lua:279>

Locals:
_ = Frame {
}
event = "ADDON_ACTION_BLOCKED"
events = <table> {
}

I'm getting the same error as OP and another one I'll post separately although I don't know what caused that one, I didn't realize it was different until I just looked back. Happens every time I change talent loadouts and then use any hotkey afterward. Reloading resolves it until the next loadout change so not the end of the world. I likely won't have time to diagnose further until after raid but will follow up later.

2x [ADDON_ACTION_FORBIDDEN] AddOn 'BuyEmAll' tried to call the protected function 'UseAction()'.
[string "@!BugGrabber/BugGrabber.lua"]:485: in function <!BugGrabber/BugGrabber.lua:485>
[string "=[C]"]: in function UseAction' [string "@Blizzard_FrameXML/Mainline/SecureTemplates.lua"]:342: in function handler'
[string "@Blizzard_FrameXML/Mainline/SecureTemplates.lua"]:667: in function <...ddOns/Blizzard_FrameXML/Mainline/SecureTemplates.lua:649>
[string "@Blizzard_FrameXML/Mainline/SecureTemplates.lua"]:681: in function <...ddOns/Blizzard_FrameXML/Mainline/SecureTemplates.lua:674>
[string "@Blizzard_FrameXML/Mainline/SecureTemplates.lua"]:723: in function SecureActionButton_OnClick' [string "@Blizzard_ActionBar/Mainline/ActionButton.lua"]:100: in function TryUseActionButton'
[string "@Blizzard_ActionBar/Mainline/ActionButton.lua"]:135: in function `ActionButtonDown'
[string "ACTIONBUTTON1"]:2: in function <[string "ACTIONBUTTON1"]:1>

Locals:
_ = Frame {
}
event = "ADDON_ACTION_FORBIDDEN"
events =

Here's the other error, pretty sure this also happened after a talent loadout change and then using a hotkey:

1x [ADDON_ACTION_BLOCKED] AddOn 'BuyEmAll' tried to call the protected function 'SpellFlyout:Hide()'.
[string "@!BugGrabber/BugGrabber.lua"]:485: in function <!BugGrabber/BugGrabber.lua:485>
[string "=[C]"]: in function Hide' [string "@Blizzard_FrameXML/Mainline/SecureTemplates.lua"]:341: in function handler'
[string "@Blizzard_FrameXML/Mainline/SecureTemplates.lua"]:667: in function <...ddOns/Blizzard_FrameXML/Mainline/SecureTemplates.lua:649>
[string "@Blizzard_FrameXML/Mainline/SecureTemplates.lua"]:681: in function <...ddOns/Blizzard_FrameXML/Mainline/SecureTemplates.lua:674>
[string "@Blizzard_FrameXML/Mainline/SecureTemplates.lua"]:723: in function SecureActionButton_OnClick' [string "@Blizzard_ActionBar/Mainline/ActionButton.lua"]:100: in function TryUseActionButton'
[string "@Blizzard_ActionBar/Mainline/ActionButton.lua"]:135: in function `ActionButtonDown'
[string "ACTIONBUTTON4"]:2: in function <[string "ACTIONBUTTON4"]:1>

Locals:
_ = Frame {
}
event = "ADDON_ACTION_BLOCKED"
events =

Decided to test immediately, ONLY BEA enabled, I don't have Bugsack enabled so I don't get the pretty error but I got this instead when I changed talent loadouts and then hit a hotkey:

Should hopefully be resolved with v4.1.1. Would you mind testing again on that version @raysmith59?

New version seems to resolve my issue so I'm good, thanks!