This may be due to changes in the sources used for remotes over time perhaps.
> There was a slight loss of -0.6 dB per decade in the cumulative threshold, but regression analysis showed the lack of a significant correlation between age and sensitivity. The intergroup analysis confirmed that infrared vision did not significantly differ between the four decades of life. The sensitivity level did not significantly correlate with visual acuity, spherical equivalent, retinal thickness or straylight parameter. The comparison of values measured at the seven locations showed a significant difference between the central (19.7 ±2.2dB) and the peripheral retina (22.5 ±2.4dB).
> There was a slight loss of -0.6 dB per decade in the cumulative threshold, but regression analysis showed the lack of a significant correlation between age and sensitivity. The intergroup analysis confirmed that infrared vision did not significantly differ between the four decades of life. The sensitivity level did not significantly correlate with visual acuity, spherical equivalent, retinal thickness or straylight parameter. The comparison of values measured at the seven locations showed a significant difference between the central (19.7 ±2.2dB) and the peripheral retina (22.5 ±2.4dB).
Source: https://iovs.arvojournals.org/article.aspx?articleid=2745068