Chimney flashing

Chimney today was originally installed with lead flashing, two years ago a new roof was installed, they “trimmed” the lead and installed aluminum (maybe metal) step flashing under the lead.

Will this eventually cause a problem with corrosion/deterioration of the aluminum/metal?

Thanks,

sounds like the former lead step flashing was trimmed and is now being used as the counter flashing.
And the new metal is being used as the step flashing.

is this the case?

mortar can/will cause aluminum to break down/corrode over time.

if it’s steel, it shouldn’t be a problem.

the counter flashing being lead should not react with the aluminum or steel step flashing.