Ask HN: How do I announce that I'm looking for a new job while being employed?

(Throwaway account for obvious reasons.)

I'm not happy working for my current employer and I'm looking for a change.

From previous experience, I know announcing it on social media can be helpful, but I'm afraid of any repercussions from my employer if they see that, and I can't afford being unemployed too long between jobs. (for visa reasons)

In the past I was open about changing jobs: I talked to my colleagues, even the CEO of the company, and they were all cool with me openly searching for a new position. But this time I'm just a row in a table for my manager's manager, and their higher-ups. So nothing that my manager tells me will give me confidence that there won't be any repercussions.

How should I approach this? Is it unreasonable to assume that there could be repercussions if I openly post on social media (including my blog) that I'm looking for a new position?

If it's not, then do you have any suggestions on how should I go about searching for a new job?

Thanks.