I'm wondering if this could be a putty bug. I can't get displayed properly Unicode Character 'RATIO' (U+2236) https://www.fileformat.info/info/unicode/char/2236/index.htm
Basically it should look like a colon but in putty to me it's just displayed as square. I started from default putty configuration and then tried various settings with Window/Appearance, Window/Translation or locales and environment variables such as terminal. Always the same issue on various windows systems. I have also the same issue with MobaXterm which I think shares putty terminal code (reported to their support and waiting for response). This bug would not bother me if not the fact that this character is used in some Midnight Commander compilations/configurations as a separator between hours and minutes in time modification column.
On the other hand Windows Terminal displays this character with no problems. Also no issues on Mac terminal.