I'm sure there is more to this than some guy's tweet might suggest. AFAIK this is the screenshot that started it:
Trawling reddit so you don't have to, this commenter suggests that the link was removed because it used a URL shortener (an automated process which happens throughout Steam):
Here are his examples of currently available mods with functional donation links:
This guy suggests another reason:
And an interesting observation from the same comment thread. There is a suggestion that Steam doesn't use that type of parentheses for removed links. Can anyone confirm?
I'm not a fan of what Valve introduced today. But there is a lot of unsubstantiated stuff flying around, including not just the removed donation link in question, but a lot of people saying they've received community bans for posting polite and rational opposition to what's happening (riiight).
There are things to be mad about today, but there are a lot of silly sideshows happening as well.