Mantra shield damage has been removed entirely for a long time, that's not new to the rework.
Also, this whole "but it was like this four years ago" or whenever Karma had her first rework really irks me. The majority of Karma players play her support. The majority of Karma mains play her support. There are probably a higher percentage of Karma mains vs average players in mid lane, but there are still more mains who play her support. Even if you liked Karma as a midlaner back before her first rework, you have to accept that she's a support now and Riot is going to balance her accordingly. Also, re: fans: Really? If the only reason you like Karma or think she's Karma is some damn fans that's entirely your problem. Karma is not the first champion to change her visuals and she sure as hell won't be the last, doesn't mean she's not Karma or that she needs to have her fans back. Also, I'm not entirely sure she isn't getting her fans, if there were pictures I missed them.
"This is not what anyone wants" no. This is not what you want, this is not what the people who have been asking for Karma to be reverted for years wants, but don't presume to speak for everyone or even a majority of Karma players.
The ally W forcing her to be balanced around specific champions is a valid concern and was also the first thing I thought of when I saw it. While it may encourage more bot lane diversity, it'll make her incredibly strong with certain mages who can fully utilize the effect and force her to be balanced around them.