What causes impaired smell and taste of different things its not covid iv already been tested and its lasted over 2+ months?

The most common reason would be infection. Given the current pandemic situation, it still most likely was Covid. It is not clear from your question whether you had a single Covid test or multiple. If your Covid test was done too early or too late, it could have been negative despite having had Covid.

If you experience these symptoms for more than one month, an ENT examination is recommended. I agree that sinusitis and COVID-19 are most likely, even with a negative test.