How to solve error The resulting array was too large in MMUlLT formula with ~9700 rows

I need to calculate concatenation of the value and how many times it was used in rows as below:

I tried to use this formula by closed-end references

=ARRAYFORMULA(IF(LEN(L3:L9700),M3:M9700&" - "&MMULT((M3:M9700=TRANSPOSE(M3:M9700))*(ROW(M3:M9700)>=TRANSPOSE(ROW(M3:M9700))),SIGN(ROW(M3:M9700)))+0,IFERROR(1/0)))

but it came out error message:

The resulting array was too large

Can advise how to solve this ?

NOTE: This is a follow-up of How to solve Error message in Google Sheet array formula: The resulting array was too large