Often in power supply schematics they use two diodes at the inputs of opamps:
What's the purpose of having two diodes at opamp inputs?
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It's because op-amps should have near 0 voltage difference between the inputs. The diodes are there so that a large voltage difference doesn't de-bias the input stage by causing the internal transistors to operate in non-linear modes. Sometimes those diodes are internal to the op-amp. Basically just input protection diodes.
That's one of the (many) reasons you don't want to use op-amps as comparators. Comparators will never have those diodes, while sometimes op-amp do have them, meaning that they will draw a lot of current and clamp when the input(s) swing.