Failing supports are not what anyone needs when using supports. Unfortunately, it happens, and can even happen to several independently failed support like in the image displayed.
Signs of failing supports:
Usually you’re using supports because they are needed for your print. If your supports fail it will be very visible as your print will not be complete.
Explanation:
Support pillars, especially when setup using a low support density are not the most stable things and will be in increasing danger of toppling over the taller they get.
How to fix:
Avoid isolated towers, place your supports in bigger groups.
Reduce printing speed for support.
Use higher support density and if your slicer supports it – a different support pattern.
If your slicer supports it, have a brim or a solid bottom layer added to your supports.