"Subscribe" and "Block" are only text, not buttons

It seems that on any community I go to (whether local or on another federated instance) the "Subscribe" and "Block" buttons appear as plain text, not as buttons/links. So that I can't subscribe to any more communities. Occasionally, "Block" will appear as a button, but "Subscribe" pretty much never does.

Example:

This only seems to have arisen in the last couple of days.

Anyone else getting this or know how to fix it?