As reported in Marlin upstream:
I have not done any testing to determine which of our FWs are affected, but confirmed in devel.
How will end users see this issue?
Most probably won't.
I already made a PR for a fix, BTW: https://github.com/MarlinFirmware/Marlin/pull/14661
Most probably won't, but to those that do, how does it manifest?
As described in the link I posted to the issue in Marlin upstream. If they run "M504" to verify the EEPROM, the runout distance will change to some random number.
Fixed in .146 and above.