String values in readFromConfig

i wrote a usermode and wanted to pass a 50-digit parameter via a string variable on the config page, but found that although it was saved in json.cfg, it did not arrive when read.
Only when I reduced the number of digits to 15 did the transfer work.
My question is this the way it should be? If so, why? Or could this be increased in the next version?

Please use serial monitor (after saving from usermod) and see if the string gets truncated by UI.