[Baertram]

Inside this function there are checked 2 settings from the table db, which is the SavedVariables of pChat where your settings are stored:

local function MinimizeChatInMenus()
 
    -- RegisterCallback for Maximize/Minimize chat when entering/leaving scenes
    -- "hud" is base scene (with "hudui")
    local hudScene = SCENE_MANAGER:GetScene("hud")
    hudScene:RegisterCallback("StateChange", function(oldState, newState)
 
        if db.chatMinimizedInMenus then
            if newState == SCENE_HIDDEN and SCENE_MANAGER:GetNextScene():GetName() ~= "hudui" then
                CHAT_SYSTEM:Minimize()
            end
        end
        
        if db.chatMaximizedAfterMenus then
            if newState == SCENE_SHOWING then
                CHAT_SYSTEM:Maximize()
            end
        end
        
    end)
    
end

They should be located somehwere below "new chat text color" and "transparency".

So there need to be at least the 2 settings chatMinimizedInMenus and chatMaximizedAfterMenus .
Search for them in the pChat settings please and if you set them to the way you like them your problems should be solved

If not - try to do the following:
Change the function MinimizeChatInMenus to this:

local function MinimizeChatInMenus()
--[[
    -- RegisterCallback for Maximize/Minimize chat when entering/leaving scenes
    -- "hud" is base scene (with "hudui")
    local hudScene = SCENE_MANAGER:GetScene("hud")
    hudScene:RegisterCallback("StateChange", function(oldState, newState)
 
        if db.chatMinimizedInMenus then
            if newState == SCENE_HIDDEN and SCENE_MANAGER:GetNextScene():GetName() ~= "hudui" then
                CHAT_SYSTEM:Minimize()
            end
        end
        
        if db.chatMaximizedAfterMenus then
            if newState == SCENE_SHOWING then
                CHAT_SYSTEM:Maximize()
            end
        end
        
    end)
]]
    
end

Added --[[ at the beginning and the closing ]] at the end so this is only a comment and not run code! But the 2 settings should solve your problem and there should be no need to comment this function then.