The TAGS menu option under Television introduced in general release 4.6.0.50 seems to pull any matching tags from other libraries into the results in the TV section.
To my understanding, the TAGS function here is to tag television and radio channels so you can add content types such as "Reality TV", "Politics", "Drama", "Radio" categorise the type of channel.
I noticed that mixed case names were often converted to lower case tags too which resulted in bizarre mixture on the display.
TAGS and UPCOMING should also be options (like tick boxes) to enable or not (default enable) under TV library configuration or somewhere applicable. Not everyone uses them.