I have the same thing. It means there's some tax form they want you to fill out.

I'm going to wait until I've got enough royalties built up to claim, then I'll fill out their form.

It's not just you

I see the same blinking if my account summary info is displayed (images in portfolio, current balance, etc.). If I click on the blinking arrow, the summary info goes away and the blinking stops.

I checked the tax center and it shows my tax info was submitted. I looked a bit in the "My account" section to see if anything else required attention and I can't see anything. I also looked at their forums and didn't see anything.

That arrow didn't blink before, so if this is a feature, they need to do some work so you have a clue what it's telling you. It's more likely some sort of bug, but as I'm just under $3 away from a payout, the only thing I care about is that the request payout feature works and the cash shows up in PayPal a few days later.

DT is largely something I ignore these days

It's so annoying.  Why fix something when it's not broken?  Can we at least have a choice to leave it as it was or ask for feedback from us which none of this was done.  We are just left in the dust as usual.

Last time this happened for me, it was because I needed to update my tax form.

That was back in December, and I notice the form still says it's 'under review'. I hope they aren't going to withhold tax for the 6 weeks that they didn't review the form?

Perhaps the blinking arrow is simply to alert the contributor to the fact that something is pending?

It happens when you have some notifications, as, for example, unread comments, photos older than 4 years and without sale, new tax form to approve, etc.

Yes, but I have nothing outstanding and nothing to action, and I'm wondering if it's blinking simply to alert me to the fact that my tax form is still pending?

It's been a terribly slow month so far. Blinking can create an illusion that there is some movement...