This tax applies only to Google. It doesn't apply to any other tech company, and it never will. The DMA at least provides more-or-less objective criteria for what constitutes a "gatekeeper", but this is literally a private deal between Canada and Google.
I don't have a problem with publishers getting a greater share of ad revenue, but there are better ways to do it. The govt could increase taxes on ad exchanges categorically (still effectively a tax on Google and Facebook) and give publishers tax breaks. That would have the same effect but be way more reasonable.
It applied to Facebook/Meta and any larger social media sites. Meta just shut it down and any direct contributions to journalism that they were making, and now the publishers are crying because their traffic has plummetted, to the surprise of precisely nobody except them.
I don't have a problem with publishers getting a greater share of ad revenue, but there are better ways to do it. The govt could increase taxes on ad exchanges categorically (still effectively a tax on Google and Facebook) and give publishers tax breaks. That would have the same effect but be way more reasonable.