Besides, it's less than 50% they're "losing". Earlier drops in Bitcoin price (around 80%) had a much larger effect on their earnings. Blocks will be fine.
And don't forget that they have been earning much more from transaction fees ever since the Ordinals spam began. And that is going to continue after the halving, plus with the added spam from RUNES. I do agree with NapHappy's logic that some older and unprofitable miners will be shut down. Let's just hope it won't have too big of an impact.
Still, I'll bet that the average fees for the 2 weeks post halving will be 50% higher than the average fees for the 2 weeks pre-halving.
The pre-halving fees have been pretty volatile lately as well. We have had periods where you needed 100 to 150 sat/vByte for a quick confirmation, but right now that's down to 60 sat/vByte.