Which of the following is/are undecidable?

For a Turing machine M, {M} denotes an encoding of M. Consider the following two languages.

L₁ = {(M) | M takes more than 2021 steps on all inputs}

L₂ = {(M) | M takes more than 2021 steps on some input}

Which one of the following options is correct?

Consider the following sets :

S1. Set of all recursively enumerable languages over the alphabet $\{0,1\}$

S2. Set of all syntactically valid C programs

S3. Set of all languages over the alphabet $\{0,1\}$

S4. Set of all non-regular languages over the alphabet $\{0,1\}$

Which of the above sets are uncountable?