According to the search with the keyword "5.624" or "5.62", we can find the story on how to find and change 5.624*****MHz (= IMC FSR ?). The latest log is klog#10286 in 2019. From 5.6244235 MHz to 5.62443350 MHz, not 5.6246235 whose changing timing is missing.
According to the search with the keyword "IMC FSR", the accuracy of 5.6246235, for example, is much better than the estimated values using IMC. So this value should be finally decided by AM sideband (or offset in the demodulated signals of harmonics) reduction as in this time? While klog#616 shows the comparably precise FSR.
klog#4831 shows how to find the best f1 (3xIMC FSR).
Anyway, IMC mirror positions were actually moved, so the IMC FSR change was expected (We forgot :( ).