Interesting observations by your urologist!

I did find another study that attempts to specifically answer your question.

Harvard Health Publishing summarizes the results of a 3 year study here:
https://www.health.harvard.edu/blog/prostate-cancer-can-imaging-substitute-for-repeat-biopsies-during-active-surveillance-202210072825
“ Upon analyzing the results, the team found that mpMRI scans were better at ruling out cancer progression than at detecting it. Specifically, the odds that an mpMRI scan would detect clinically significant cancer (the kind that needs more immediate treatment) that a biopsy would later confirm ranged from 50% to 57%. By contrast, the odds that a scan would correctly show the absence of worsening cancer ranged between 82% and 86%.

Based on these results, the investigators concluded that men with negative mpMRI scans can safely omit the one-year confirmatory biopsy. However, men should still get a standard three-year biopsy, they wrote, "due to occasional MRI-invisible tumors." The team plans to follow the men and present 10-year data at some point in the future.”

Others are still taking a more conservative approach:

"This study adds to better understanding the utility of mpMRI in the continued evaluation of men on active surveillance," says Dr. Marc B. Garnick, the Gorman Brothers Professor of Medicine at Harvard Medical School and Beth Israel Deaconess Medical Center. "The upside of the study is that more biopsies can potentially be avoided. The downside is for patients to understand that the MRI is not an equal substitute for biopsy: a negative MRI finding may have missed a clinically significant cancer. In my own practice, I have used MRI to monitor men, along with digital rectal examinations and PSA evaluations on active surveillance instead of repeated biopsies, but only with the patient's full understanding that a small number of potential clinically significant cancers may not be detected by this practice."

Sounds like your urologist is in the later camp.

Here’s a link to the paper and the “final analysis” conclusion.
https://www.auajournals.org/doi/10.1097/JU.0000000000002885
Conclusions:

“Final analysis of the Magnetic Resonance Imaging in Active Surveillance trial indicates that there is minimal risk to omitting 1-year confirmatory biopsy during active surveillance if baseline magnetic resonance–targeted + saturation template biopsy was performed; however, standardized 3-year systematic biopsy should be performed due to occasional magnetic resonance imaging–invisible tumors.“

All the best!