The limits for recursion have undertaken a significant change. (Though it might not be that concerning, if you see my sibling answer).
> As already discussed, Lua 5.4 is using a "non stackless" implementation. That means that it uses the C stack for recursion in Lua functions. Because of that, the maximum depth of recursion is much lower in 5.4 than it was in 5.3. - Roberto Ierusalimschy