I have observed some occasional delamination in horizontal layers of my resin prints — see two examples:
What is the cause, and how can this be minimized?
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With the information provided my thought is that your layers are underexposed for their thickness. Each layer is just barely bonding to the layer above it. After being pulled on by layers below eventually one of the layers fails. This is especially likely to happen on a thin part of the print any may need more support if it is followed by wider layers. But I would suggest trying to increase your exposure time first.
option two: it could be your FEP if that has seen too much use it may be time to replace it.
Besides the options of underexposure or bad FEP film, there's also the option of the print being in a bad orientation for printing. Often, the quality gets better if you tilt the model some degrees. You do have to clean up some places, but the stresses from pulling free of the FEP get distributed more evenly and are lower, resulting in generally better prints.
Other factors that can impact the print quality is the resin's viscosity: the more viscous, the more likely resin can't flow in enough. Resin's viscosity is antiproportional to the room temperature - the hotter the room, the less viscous the resin.