Oh I know what happened. The recent change was that many punctuation/special characters are now excluded/disallowed from tags, which made your tag @1/01/20 get recognized as @1 instead. It seems like tags require at least a character thatās not a digit, so @1 wasnāt even recognized.
This change was put in about 2 months ago, at least on the web version. Originally, the fix was intended to catch situations where one would write @person1/@person2 which would be recognized as a single tag (See: Mentions/tags include common punctuation)
Iām thinking a solution would be to treat / as part of the tag unless the next character is #, @ or a space character.