It is not clear to me whether you are asking to come to work in Germany short-term , for example being sent by your current employer in Poland to work for two weeks in Germany, or if you are considering coming to work and live in Germany.
If it is for short-term work purposes, then the A1 certificate is necessary. It is proof that you continue to be employed and covered for social security purposes in Poland. As a TRC-holder, however, you also need a visa form the German embassy in Warsaw which allows you to come and work here. The A1 certificate is only related to social security and does not have anything to do with immigration law or work permits.
If you wish to come and stay long-term, the A1 certificate is not relevant. In this case, you apply for a work visa at the Germany embassy in Warsaw.
Please note that for beneficiaries of temporary protection from Ukraine, the rules for coming to Germany from Poland are simpler.