Command block kicks due to too many characters.

When pasting in any string over length 256  in a command block I am kicked with the following message:

Internal Exception: io.netty.handler.codec.DecoderException: The received string length is longer than maximum allowed (347 > 256)

Aside that, I am aware that the command block maximum input is 256 characters now, but this seriously breaks alot of maps and commands that were longer. For example, you can no longer get player heads with custom textures from here:

https://freshcoal.com/maincollection

Thank you!