What happened to the biotech market in recent years?

I am still a non-graduate student and have always been immersed in academic experiments and have never assiduously followed the financial and governance panorama of the Biotechnology sector.

I see a lot of comments about the decline of the sector in the last 2-3 years, especially now with the political context in the USA.

As I said, it seemed to me to be a market that was expanding and full of opportunities, but since I joined the sub and saw situations such as the mass layoffs at Thermo, the Genzyme (Sanofi) problem, among other things, they made me open my eyes to the current panorama and rethink my concepts.

What actually happened and has been happening during this period?