Take 50% less, until you get a better offer. The job market will pick up again.

There is no guarantee that your current stable job will not suddenly come to an end for many reasons. Outside of a few rare companies, there is absolutely no reason to stay, if they are not paying you market rate.

I guess it depends on the region. Recently, I have quit a job to get a 15% increase (I know, it’s not a huge increase but I am already hitting this glass ceiling around here in Europe for senior developers)

15% is a huge increase for most. I've never seen a 15% increase at one time.

I got a 20% increase the other year. But only because I threatened to quit aggressively and got promoted in the same year and was valuable to my small team of ~4 engineers.