As mentioned here we are planning on updating systemd to v251 soon. Systemd v251 dropped support for kernels older than 4.15, so at that time we expect that users still using the 4.14 kernel will no longer have a successful boot. The fix for this is to choose a newer kernel from the boot menu (I usually just hit the down key during booting until it appears).
If you are for whatever reason still using kernel 4.14 (check the output of uname -r) then I highly recommend you check to see if a newer kernel will work on your system. Linux-lts has already been upgraded to the 5.15 series while linux-current is on 6.0 (for now), both kernel seem to be working for the vast majority of systems and are likely to work for you as well.
