Undefined field gsub for string:gsub

[serg3295]

Describe the bug

To Reproduce

local optparam = {}
local allop = {}
for op in string.gmatch(allop, "[%[%s]+([%s%w_\1\2\3]+)[%[%]]") do
  optparam[#optparam + 1]  = op :gsub("\1", ",")
                                :gsub("\2", "[")
                                :gsub("\3", "]")
end

Environment (please complete the following information):

• OS: Linux Mint
• Is WSL remote?
• Client: VSCode

[Avril112113]

I am having the same issue in multiple places in my own code.
Looking into this more it's a bit strange when it happens, here is a list of minimal examples of what I've found so far so work and not work

local str = "123"

local working1 = str:gsub("0", "1"):gsub("1", "2"):gsub("2", "3")

local broken1 = str:sub(2, -1):gsub("1", "2"):gsub("2", "3")
local working2 = str:gsub("0", "1"):sub(2, -1):gsub("1", "2"):gsub("2", "3")

local broken2 = str:gmatch("%d")():gsub("1", "2"):gsub("2", "3")
local working3 = str:gsub("1", "2"):gmatch("%d")():gsub("1", "2"):gsub("2", "3")

Extra note: no errors in the log file