Brakes Finally found the slow leak

Some time back i noticed loss in stopping power.
Having fairly recently done brake maintenance, new front and rear hardware and pads, new clutch, and replaced all lines, soft and hard (rust belt) i figured it had to be trapped air... bled, the problem persisted but wasn't too bad so I just continued to lived with it...

Then came a yearly inspection the shop wouldn't pass me, so i took it back changed the master cylinder, changed the slave cylinder, now everything but the booster was new... bled over a quart of fluid through the entire system, same problem...

Took it back in for inspection, knew id done my best and welcomed them to fix the problem, which also ensured the car would pass... Well i got it back with a bill for bleeding, they 'claimed' they got a bit of air out... i knew that wasnt true but at this point i was just paying a bribe to pass inspection...
So the problem persisted and i kept driving...

Fast forward a year or 2, recently ive been using the car less due to the kung flu, I noticed the back wheels locking up... so bad that they would drag for a bit before breaking free.... figured id now fix perhaps a parking break adjustment, well i checked finding the mechanism stuck...
I pulled the drum removed the the parking break mechanism and opposed to a nice dry dusty drum I found this mess:


There was also a small hole in the wheel cylinder boot from the parking break jamming up against it...

As i said the drums were recently done so i didnt figure there was a problem... but a slow leak into the drum was causing the soft braking as well as building up with the dust and corroding the hardware...

Got new wheel cylinder kit off rockauto for 1.40$ or so, the seals were noticeably worn down, that was a rough lesson in wasted time and money