Thank you all for the responses.
This install predates 4.0, I don't know exactly how old, but it is very old... and while installing I created a 300MB boot partition, because I had problems with the installer back then.
brent Yes, I removed older kernels, and uninstalled linux-lts too, also removing the lts kernel, all I have now is:
com.solus-project.current.5.13.6-190
com.solus-project.current.5.13.4-189
Together they are occupying 138,3MB now, but I know I'll have to expand boot to not have this problem again, my question is can I do it safely? I have had terrible problems in the past with resizing partitions, tooks ages and lost everything, my first HDD has just /boot and solus, which partition is lvm installed with the installer...
Can I safely move /boot inside this lvm and tell grub/legacy where solus is?
Maybe some other Idea? my second HDD /data, has my lovely important stuff, I won't dare to touch it.
PS.: I was told that lvm partitions are much easier to resize/expand, but never tried, I fear losing my system.