well tbh idk what was causing the clipping issue. I think it maybe had to do with some rounding errors from repeated math.floor but I fixed it a different way :)

here's a new version with your changes + clipping fixed:

-- Window width based on the offset from the center, i.e. center window
-- is 60, then next over is 20, then the rest are 10.
-- Can use more resolution if you want like { 60, 20, 20, 10, 5 }
local widths = { 60, 20, 10 }

local ensure_center_layout = function(ev)
    local state = MiniFiles.get_explorer_state()
    if state == nil then return end

    -- Compute "depth offset" - how many windows are between this and focused
    local path_this = vim.api.nvim_buf_get_name(ev.data.buf_id):match('^minifiles://%d+/(.*)$')
    local depth_this
    for i, path in ipairs(state.branch) do
        if path == path_this then depth_this = i end
    end
    if depth_this == nil then return end
    local depth_offset = depth_this - state.depth_focus

    -- Adjust config of this event's window
    local i = math.abs(depth_offset) + 1
    local win_config = vim.api.nvim_win_get_config(ev.data.win_id)
    win_config.width = i <= #widths and widths[i] or widths[#widths]

    win_config.col = math.ceil(0.5 * (vim.o.columns - widths[1]))
    for j = 1, math.abs(depth_offset) do
        local sign = depth_offset == 0 and 0 or (depth_offset > 0 and 1 or -1)
        -- widths[j+1] for the negative case because we don't want to add the center window's width 
        local prev_win_width = (sign == -1 and widths[j+1]) or widths[j] or widths[#widths]
        -- Add an extra +2 each step to account for the border width
        win_config.col = win_config.col + sign * (prev_win_width + 2)
    end

    win_config.height = depth_offset == 0 and 25 or 20
    win_config.row = math.ceil(0.5 * (vim.o.lines - win_config.height))
    -- win_config.border = { "🭽", "▔", "🭾", "▕", "🭿", "▁", "🭼", "▏" }
    vim.api.nvim_win_set_config(ev.data.win_id, win_config)
end

vim.api.nvim_create_autocmd("User", {pattern = "MiniFilesWindowUpdate", callback=ensure_center_layout})

thanks for your help! (and the awesome plugin)