A pressure washer can be fitted with a sand blaster attachment. That
may be too severe, or at least risks brick face damage.

However I'm sure Tommy Walsh had an angle grinder (looked like 9")
with a large flat disc with a pad on it which was specifically to
remove paint without damaging the face of bricks. Once the face has
gone you are screwed, a few wet winters will trash them quite quickly.

The material on the disk was arranged in a raised spiral pattern, I
suspect not too different to a 3M Clean n Strip disc - but much harder
because they wear down very quickly when removing even small paint
spots from brickwork.