The main answer to your question is that true and anti-dependences can cause pipeline stalls and reduce performance in the MIPS 5-stage pipeline.
An explanation of this is that true dependencies occur when an instruction depends on the result of a previous instruction that has not yet been completed. This causes a stall in the pipeline as the dependent instruction cannot proceed until the previous instruction has finished. Anti-dependencies occur when a later instruction depends on the result of an earlier instruction that has not yet been written back to the register file. This also causes a stall in the pipeline as the dependent instruction cannot proceed until the earlier instruction has written its result.
In conclusion, true and anti-dependencies can cause significant performance issues in the MIPS 5-stage pipeline. To address this problem, techniques such as forwarding and pipelined execution can be used to minimize stalls and improve performance.