Currently on Solus has 2 options for kernels:
- LTS (currently 4.9) - Long Term Support, which few people need to use if they have compatibility problems or need to use proprietary Nvidia driver for old cards (340).
- Current (currently 5.5.7) - the default, as new kernel as possible that doesn't cause problems.
If something is broken with a kernel, you should report it so it can be fixed for everybody.
Also when updating, system will keep the previous one, if something goes wrong. And you can boot to it if you press space repeatedly during boot.